Either way, it seems like you'll be without a car:-
Honda Prelude: Probably alot of time spent off the road & in the workshop getting body kit, paintjob, other mods + 'MAJOR RICE LABEL'.
AE101: Time off the road getting an engine conversion.
MR2: Time off the road getting repairs for what is a 10 year old car (I'm assuming it's a AW11 you're referring to).
Which leaves the Merc: You're just 21 ... anyone will say it's your folk's ride. There'll be lotsa time for this when you have a family later on. 2 seater cars won't be at that stage ...
Me therefore suggests ... GET A HYUNDAI!!!!
But seriously, you have to stop & think. You've started the process so think it all the way through. I just hope you're not like this when it comes to women ...