So I popped in [size=+1]GT1[/size] and checked the green-striped Viper. Cr12,000/Cr10,000 for used car trade, and Cr35,000 to purchase from memory card.
I can't recall whether I have the starter garage (from Playstation Underground?) anywhere. Did they make versions of that for PAL and US?
I vaguely recall some of the cars were oddly priced.
If you use a game shark, or examine the garage structure each car has a value listed in the garage, which can be changed with a game shark. Once in the garage, the value is independent of the model. (The values are a table separate from the main car structures).
Now, as far as I recall, when winning prizes there is nowhere in the prize table which sets prize car values; that seems to come from a central table somewhere; when I used a game shark to win used cars they had value zero sort of like the B license Concept Car and I couldn't change that, and if I could it wouldn't be convenient.
There's some possibility the odd prize price was in version 1.0 and fixed in version 1.1 which I used. Note that the car value would not change if you view the same garage in different versions because the value of the car is literally stored in the garage. It's unlikely I will ever get the energy to win a green-striped Viper in version 1.0.
It's more likely I'll find my magazine disk starter garage and check the price there.