If it's for mini, you want something with negative camber, adjustable shocks maybe so you can adjust the rebound rate, and maybe some coil over shocks to adjust the height. I haven't built my buggy yet so i can't help you much, Sorry :-\
Max
Are the engines going to be front or rear mounted, will you be using the Mini subframe or will it be a custom one? If you're using the Mini one is it dry or wet?
The engines are rear mounted on the original subframe. I have gone for AVO fully adjustable shocks. Seemed to be mid priced, but will do the job nicely. (hopefully)!!!