Quoted from xTheBlackKnightx:

The best advice to any new NIB buyer is quite simple.
A person should wait until a game is actually released to allow you evaluate the product, even if through electronic social mediums, if a game is not able to be tested in person.
There are simply so many reasons for this advice, and I will only share a few key aspects.
If a person can afford a NIB game, they can afford to travel to test play a game for a single weekend.
Did enthusiasts know you can contact Stern and ASK where they will be planning to test play games on location?
Go to Las Vegas for a weekend, as every single new Stern game shows up in New York-New York casino within a month of production.
You pre-purchased a game that is still in development, and is the #1 mistake of new buyers.
There should be no rush to buy a product in this industry.
There really is no significant advantage, regardless of what manufacturers try to tell pinball enthusiasts.
This is simply marketing.
If a person wants to place a refundable deposit, that should be the limit of the decision.
If the game is successful, it will be available for years after it is produced, either new or used in HUO condition now based on the market.
This includes LEs.
This is not a wood rail pitch and bat collectible baseball machine made in the 1950s.
This is the not pre-1999 when games were not as readily available in the private consumer market.
If I want a game, I can normally find a superb+ example of any machine title within three months unless it is truly rare either due to extremely low production, sample, or prototype status.
Even then, based on resources, I can normally find an example within a year or less.
Anybody that says "this is impossible", feel free to talk to me, and ask for a game they want.
However, be prepared to pay for a quality example, and not be thrifty, if they want a nice example.
You cannot pry a rare machine out of collector hands for pennies, sometimes not even for money, but rather in parts such as playfields, backglasses, and assemblies.
That really is the source of enjoyment for most collectors after the first 5-10 years of collecting anyway.
Any game produced in the past 15 years, does not qualify at all, unless you believe that a BM66 SLE will never be available on the open market, which will occur as well, most likely in less than 6 months, and probably will show up here, after the new owner gets tired of their toy.
Focusing on protecting something that has not been evaluated is not particularly helpful, as you do not know what needs to protected in the first place.
This is like protecting the "Invisible Wonder Woman" airplane leather cockpit seats with Armor All.
I can estimate concepts of problem areas noted on playfield design already, but photos are like game flyers, features actually do CHANGE.
There are plenty of basic maintenance areas already noted, but not a single one are game specific.
The decision to buy early is made hundreds of new times a year, based on instant gratification concept, and it seems that many must make this fundamental error at least once in this hobby before they learn the lesson.
That is of course, unless there is no concern regarding disposable income.
It really is not about the money itself, but more about what a buyer is receiving FOR THEIR MONEY?
What basic pinball feature will Stern strip out of Aerosmith from their previous title?
It has happened to every single game produced since 2012 starting after Star Trek.
Look closely at the features breakdown sheets of all their games, and see the changes.
Learn and prepare to be surprised.
This excludes any additional considerations of Stern's quality control production, code completion, or production delays.
I have no doubts that Stern's latest reveal with actually built and shipped in a relatively timely fashion, unlike all other manufacturers, but technical issues are generally discovered after a game has shipped.
You can almost guarantee that the code with be at most 80% complete at best case on shipping release.
The days of "flipping power" to sell a game for a minimal loss if you do not like the game, it has problems, or has design flaws are coming to a slow close.
There are many collectors that wished they listened this advice when they bought games like KISS, WOF, WWE, 24, Shrek, Avatar, etc.
For every "hit" there is at least one bomb, regardless of quality of artwork.
Sometimes there are 2-3 in a row before they have a "winner".
"You can expend as much effort as you want protecting a problem child, but the child is still a problem without corrective action."
- TBK
Nobody is punishing Stern for their mistakes, people keep readily accepting certain issues as "normal business industry challenges" or out of nominal ignorance.
Some problems definitely are challenges, but some are simply excuses for cost cutting unbeknownst to new enthusiasts.

Quoted from xTheBlackKnightx:

Plenty of sources for assistance.
Here are a few other sources I have bought true "HUO" (or very close equivalency) machines in the past 30 years other than private owners from collectors:
- Operators that buy more than one game in volume, and place them in their home
- Operators that buy more than one game in volume, and keep them in their warehouse NIB for years
- Distributors that buy a game for display for operator sales
- Distributors that buy a game for personal use
- Dealers that buy a game for display for home use sales
- Dealers that buy a game for their personal use
- Dealers that sell display games to employees
- Designer's private games
- Games given to manufacturer employees as gifts and later resold
- Manufacturer samples never placed on routes and sold directly to collectors
- Manufacturer close out games
- Games that have been forgotten in "time travel" warehouses or on resold property
- Games that had "infant mortality syndrome" after being placed on a route, and electronics failing, and never repaired
I can give title examples and circumstances of every single category, if someone is truly interested.
The games do not always come from collector's homes exclusively.
This is something that has only really begin to change in the past 10-15 years.
The home market is not the only "savior of pinball".
When the economy sometimes went south, operators picked up the pieces.
However, this is no longer entirely the case, but the games remain in the all sorts of opportune locations.
People just have to expand their horizons of thought, and stop believing that the only way to find a high quality title is through home use, not that this direction is a poor choice.
Some operators still take better care of their machines than home owners, have much more experience, and understand why they should. The reason is direct, resale value, if there is insufficient income being made on a route.