I wanted to learn how to work on 1911's from a gunsmith perspective, not so much as carrying one, (that's what glock 27's are for I thought,) so I bought a rattle trap beat to snot springfield GI. Not a bad gun out of the box when new, but this used one, it didn't have a tight part in it.
Originally it shot a 10 inch group at 25 yards, and that was with both myself, and a pistol competitor at our club shooting it. Horrible, I know. So I welded up the barrel lugs, and the hood sides, and bushing, and then put then in the lathe and trimmed them appropriately. A longer link and some lockup work helped to get the barrel higher into the locking lugs in the slide as well. Then I welded four pads in the rails, extreme front, extreme rear, both sides. Then I milled them so that the slide is loose on its way back and when picking up the next round, but at the position of full forward lockup the rails get tight again. That took five hours right there, which includes the hand fitting with flitz polish and sand material. The rails look ugly when the gun is apart, but I don't care, you can't see them when it's running and they are perfect. Loose enough to feed reliably and tight as one piece of metal when you pull the trigger. After this work the gun shot 3 inch groups at 25 yards with the exact same ammo. So far at this point in the project, I spent 400$ on the ratty gun, and about $25 on a link kit. Everything else was done on the mill, or lathe, (or with a dremel, eeeekkkkkk) and I used up maybe $3 worth of wire and gas with the mig. Grand total, $428, to shoot 3 inches at 25 yards. I know with a ransom rest and a match grade tighter chamber barrel it'll shoot better still, but from a sand bag with a worn barrel I'm happy.
Then I ordered a larger beavertail, safety, slide stop, plunger tube, pin kit, etc. etc and after fitting those parts I decided to also bobtail the grip. I didn't buy a bobtail kit and guide, I re-pinned and shaped the orignal mainspring housing. This left a huge hole where the spring was, so I welded that up too. Another 3$ in wire and gas. Originally I wasn't going to carry the gun, but now that I've fallen in love with it, it's personal to me, so I bobtailed the corner off so it doesn't print as bad.
I built a standard looking gun that shot very well for less than $500 including the transfer fee. But that wasn't enough. I had to fit all the gizmos, and do all the "cool things" just to prove to myself I could. Trigger job, (bought the guide), checkering the front strap and top of mainspring housing, (bought the files) and after another $400 in parts and tools I have all the cool stuff installed. (Sans compensators and optics, this is a carry gun,) and after I spend another $200 it'll be refinished and it'll be gorgeous too.
Moral of story? You can build almost anything you want, or need, for less than a grand if you have a mill, lathe, welder, and/or access to them. If you don't have those things, go on ebay, spend $500 on old worn out used mills and lathes that people are hauling to the recycler, and learn to recondition them and use them. I did, it was fun, and well worth it.
Don't let ANYONE tell you that you can't do this. Now wear safety glasses and get to work!!!!! Enjoy.