Your choices for chassis are really Talon motorsport or Saturn which i think are now trading under NTS.
Why not use the 3 series as your donor?
The other option of late is the Mx5 as there are lots of tuning options.
Here is one on ebay;
http://www.ebay.co.uk/itm/Haynes-Roa...item1e6b99fd47
(put your location in your profile as this will help also)