Ahem, I race vintage, so somebody does.
Hard to have an opinion on the MGA with so little information. Particularly with a race car, much of the quality of the car and what it needs has to do with the details-- what's in the engine, what's been done with the suspension, what transmission, etc., etc.
Also, with a vintage race car it is important to know what organization has accepted it. I understand from this is a VSCCA car, which means it would probably be accepted anywhere. The car is listed at $25k on the dealer's website, which is ridiculous, especially since it sounds like the motor is barely beyond street prepared and it just doesn't look very tidy. Though, again, there is very little to go by. I'd guess the reserve is at least $20k. Previously it got bid up to around $9k. Not sure I'd believe the supposed one bid at $12k now.
The fuel cell, for example, is a cheap POS type that I'd immediately want to replace with a real one. Shows that the builder was cutting corners, so who knows what other compromises were made. I'm surprised the car has been raced without a bulkhead between the trunk, where the fuel cell is, and the seats. That's a big no-no in most organizations, but maybe VSCCA isn't as concerned about that. Maybe they consider the trunk floor the bulkhead, but that cheap fuel cell has the fuel lines connected to the plastic liner. If you got rear-ended in that car the lines could break off and you'd probably get doused with fuel.
Compare that car (and ad) with this one:
http://www.hemmings.com/classifieds/cars-for-sale/mg/a/1714852.html
Now, that looks like a well-prepped car with all the best in the motor and transmission. And probably a bargain at the price. The problem with that one, though, is venue-- many vintage racing organizations won't accept the tube shock conversion and the T9 gearbox and I don't know what else. Neither of which are in the '72 GCR, BTW, contrary to what is represented.
Bottom line, the red MGA is probably a $10k car as it sits, and you'd probably put another $10k into it to make it a really good race car. Though you could probably race it pretty much as is (PLEASE fix the fuel cell) and toodle around at the back of any given pack.
Vintage FF is a great way to go, but the entry fee for a decent car would probably start around $18k. FV is the cheapest entry point at a few thousand for a car, though I understand parts are getting tough and more expensive.
Well, you were craving opinions, so that's mine.