A 2021 Model Y Performance w/FSD cost about $71,000 new (and wasn’t eligible for the $7,500 tax credit) – always best to find somebody else to pay the first few years of depreciation {{ LOL }}.
If you can keep your annual income below $75,000 ($150,000 for married filing jointly), you get a $4,000 credit on the used Tesla, dropping the price to $21,000.
If you buy it from an individual or from a dealer, it will transfer. If you buy it from Tesla, it will only be included if it is explicitly listed in the used vehicle feature list (some of their used vehicles have it included, and some do not, some vehicles that had it previously are listed for resale without it).
Be careful, as some less than scrupulous dealers are listing their prices AFTER the $4000 used EV tax credit. Obviously not this one, though.