I own alot of the GT300 cars
the Wedssport Celica is a very good fast and stable car right out of the box at it's only 200,00. THe Suburu BRZ Gt300 base model and the RX7 Gt300 base models are both stable and well handling.The Lexus IS350 GT300 base model and Weds Sport handles well but they need a little tuning on the tranny to make them faster
A good cheap alternative is the Nissian C west Razo Silvia @ 75,000 but it has a lil bit of unsteer to me and I upgraded to engine tune #3 cause it was a tad slow at 490 pp
out of the 3 Gt500 cars I own I prefer my Lexus SC430 GT500 Base model.Its is very stable and handles well. The Honda NSX GT500 Base model and the HSV-110 base models I own are a tad faster than the Lexus but both need alot of tuning and they aren't as predictable to drive as the Lexus in my opinion