I found some websites having cheap price but don't guarantee they are the cheapest.

TA05R-IFS:http://www.precisionrc.com/nv/car/pr...oduct_id=54406

Cyclone S:http://www.ultimatehobbies.com/istar...=HPI66405!1007

If you can afford a little more, here are other two choices

TRF415: http://www.tamiyausa.com/product/ite...oduct-id=42104

TC5: http://www.amainhobbies.com/product_...ducts_id/14047

I would say if you want a cheap but upgradeable car, go for Cyclone S, you can make it like Cyclone TC step by step, they are pretty identical except the lower chassis deck and different material for the parts. Of course you can do the same thing for TA05R but you may need more parts for the conversion (I mean to make your low end car "look" like a high end car). However TA05R already has some goods in it like TRF damper, CV joint, carbon reinforce chassis and suspension, and some aluminium parts.

If you can afford TA05R-IFS, I would strongly recommend you to buy Associated TC5, just add 50 bucks more you can have a race version car, no need any carbon fiber upgrade , and it is easy to get parts on some American online shops.