Looks like a good space so do it right. Start with a proper permit for the work being done (especially under home) and shop local references for licensed contractors on quote/bid. Good luck!

I would go with a fully licensed contractor for something like that, and they should have no problem getting permits for the job if they are professional. This is your house, and besides the inherent risks of an improper job, having something like that will definitely affect the possible future sale of the home.

Probably like just about any project, anything can be done. Its just a matter of paying.... I have no idea what the number would be, but probably closer to 120k than 12k.

Also, I'm no expert or anything, but what's under there right now looks a bit suspect, especially some of that bracing. I know there are some Pinsiders who are contractors who know about stuff like that, maybe they will find this thread and comment.

What's the total available height you have in there? Can't tell from the photos.

Okay, here's the tricky part. Looking at those pictures, it's definitely possible, but you're going to need an entirely new support structure to make it happen. I can't tell if that's all concrete, or some of the supports are on dirt. With dirt, there's what's called the angle of repose. When something sits on the peak of a pile, the angle of repose is roughly 45º. The force from the column follows that as well, so you really can't dig out the dirt from under some of those columns.

You will likely need to have an architect/engineer spec out a whole new beam system under there to do it safely. Honestly, given the option, i would build an attached structure next to the house.

If you have a 14' work area, I would keep to that area. Underpinning or digging out your basement would just balloon any cost estimates. Definitely have that project permitted. Having your house fall in is not worth the savings.

I’d never do anything without permits. When it comes time to sell, you may be forced to UNDO all of the work which will cost an ass ton of money and be a major headache. It’s totally not worth saving a few K.

About heat and ac, I find on a basement level it’s not very necessary. It stays cool in summer and warm winter due to being underground. You can always use a space heater and dehumidifier to control the climate a bit. Hope you get your game room.

Check where your water table is before doing anything.

How big (width/length) is the area you’re planning to finish? Hard to tell from the photos, but from what I see the area available to be finished doesn’t look very big.

That’s the biggest damn “crawl space” I’ve ever seen!

I’ve worked in the trades with some wild guys who have dug-out basements on the down low. They do phenomenal work, but if selling is at all on your mind, then you should get a permit and have it done right. Plenty of competent contractors don’t pull permits because some towns and building inspectors are idiots and REQUIRE you do things the WRONG way just because of outdated codes and their own hubris and ignorance.

Just be careful what you’re getting into, ask around and always get multiple quotes!

Is a standalone building somewhere on your property not an option? (Seems like that may be a “path of least resistance” type of way to go.)