I've heard that there were people on here that offered repair services, but no one's heard from them for a while, so that's why I'm still looking for help and parts. From what I'm told, though, the RF is usually flaky, and as far as chips go, the VDP chip and one or both of the ROM chips are the most prone to breakage (which is why you get the staticky or black screen with/without beep).
For building up parts, Ksarul has made a lot of offers to us, and mentioned he has several working and non-working TIs that he can share with those who want to get back into the community. If you want to try working on them for learning how ot fix them up for people like me, then he's probably your best bet to go to for parts for that. I've not had that best of luck on Ebay, but make sure to check the relevant post for any deals people find on there.