Can someone please tell me which aftermarket radio i can buy and i would still be able to use my control buttons?

 

no aftermarket HU will work with your buttons

the only way it'll work is if you get the DCI
DCI works with all brands

 

If you buy a head unit that have a remote, it'll solve your problem. I personally can't stand having my volume on the left side anyway.

 

search for a modifry dci. The best product for the job, and was engineered specifically for the s2000.

 

Modifry DCI -- just as the posts above suggest as well as the handy Audio FAQ stickied at the top of this very subforum.

I can't stand not having them. YMMV, of course but the OP specifically requested info on retaining the controls.