Look, this all depends on your goal for your own collection. If you know you MUST get game X and you're going to love it, pay a little more to ship yourself that game because who cares? You're going to keep it.
If not, there is no problem in casting a wider net, picking up a few games for your space, and then turning them over when you decide it's time for something else. If you're looking for multiple titles, there is really no reason that you can't do this. Back when I started a long time ago, I wrote down about 40 pins I was interested in, researched their average prices and noted the low end of it, and then updated the list every so often. Whenever one of those pins showed up at or under the price I had on my sheet, I'd buy it.
Once in a while, interesting games would show up that weren't on my list but were great deals. I'd buy them and if nothing else, play them for a while before I sold them again.
Did I have space for all those pins? Nope - but in doing so, I got to experience a lot. With EMs in particular, if you see a machine show up for sale that you're sort of interested in within your local area and it's a good price, get it. Then, when you start getting full get pickier.
My list got down to basically just BBH not too long ago. I could afford to be picky and wait because I wasn't just trying to fill space. My other games were entertaining. After about three years of waiting, a BBH popped up locally, and I happily snagged it.
I found it a decent way to go.
Quoted from Boatcat:
Are the desirable titles gone? I'd say so. The hobby is no longer in it's infancy, and those great Wms. Games of the 90's are at or approaching their 20th birthdays. Finding one, or a classic EM reasonable these days is usually considered very lucky.
It's all perspective. Pinball is sort of unique because you can sell games for usually about the same price you buy them for. If I buy a TAF for whatever, play it for a year and sell it a year later for the same price, that's pretty reasonable. When I started, game prices were MUCH cheaper for a lot of titles than they are today, but people didn't go, "Well, that BSD for $1k? KILLER deal!"
No, they said, "See if you can talk them down to $800. People were giving away BSD's last year! It's a DOG!" (note - back then, most people were route operators, and BSD was a route dog).
I could have picked up TZs for under $2k *all day*, and yet people found that price pretty unreasonable, believe it or not. The difference was that back then, when your TZ clock broke, you were screwed. Or if it had broken plastics, well, live with it unless someone is parting one out. The repro market was pretty non-existent, and it was expected that a game that you picked up would go down in value by the time you sold it. That $1k BSD? You'd put $500 in parts into it and sell it for $1k again.
I see the hobby as remaining reasonable. The only way it isn't is if the market for just your games crash. Otherwise, if everything remains relative, you will be able to get the same value in "future games" out of your games at whatever price you pay.
Hope that all helps someone in some way - I have no idea how