Shop out on TFTC isn't too bad. The ramps are a bit of a pain because there's some overlapping going on. They're only coming off in 1 order and the same is true for putting the back on.
The most common issue on a TFTC is for it to have either a damaged or missing door handle shooter. There should be a door handle, a half head cover, and the launch "button" is the tongue of the head. Frequently, the head and / or handle are missing completely. When they are there, it is commonly chipped, especially the tongue.
Eyeball targets can break. Again, not sure what the availability is of those.
Decals for the drop targets and tombstone used to be available. Probably still are somewhere.
Other common issues with this game are the VUK (as has been mentioned) and the tombstone (which is motor driven). I never had issues with either when I owned the game (for about 3 years), but certainly things to checkout when purchasing.
I'm not sure if the topper was standard or not. Mine didn't have it when I bought it. I bought one, but they weren't cheap, even 10 years ago. I'm not sure how readily available they are now. One of the best toppers in pinball, though (and I'm not big on after-market toppers).
It was a fun game. Wives / girlfriends will hate it. The Crypt Keeper never shuts up. Lots of good call outs, though. Double jackpot is one of the better in pins, I think. Good humor, too. I'm suddenly wondering why I ever sold mine. Damn you!
(good luck with your search)