Hi Aaron
As Juls said, they have stopped making Spyders (& Libra's) and only made about 40 Spyders in total. Think you'll be lucky to find an unbuilt one & if you do, you'll probably have to put it through an IVA test now.
When i owned several kitcars back in the 80's/90's, i used to buy them ready built and then strip & rebuilt them as necessary. Used to work out cheaper than buying a kit & donor vehicule.
Depending what your budget is, there's one on ebay at the moment.
http://www.ebay.co.uk/itm/GTM-Spyder-1- ... 2a309830dbBest of luck
Sven