What do you plan to do with the car? If you are interested in Tracking then how serious do you plan on getting? What is your goal for your driving skills? As your skills increase so does the speed and your need for more safety equipment.
At the track I have seen very nicely modified E30's and E36's. SPEC E36's are an affordable platform for serious Tracking. Many are available and many are already modified with the right equipment. And if something should break, it won't break the bank.
My favorite track car right now is my friend's Turner Motorsports prepared E90 328. He bought it "slightly" used.
It has everything and he flys!
ESS VT-1 550 | M24 Oil Cooler | Fall Line Half Cage | RaceTech 4009W | 6 pt Harness | Lifeline Zero 360 Fire Suppression | Rear Seat Delete | Motion Control DA Dampers w/remote reservoirs | 900/650 Hyperco Springs | RD Sport Sway Bars | Brembo 380 BBK | GC Camber Plates | Hoosier R7 | Eisenmann Sport | Stack Gauges | Painted Challenge Front Lip | Painted ZCP Rear Spoiler | Xpel Ultimate Film | LuxAngelEyes