An electric car conversion, even after removing the ICE parts generally adds quite a lot of weight to most cars (so much that they generally have to upgrade springs). You might be able to go with Lithium-Ion batteries for that kind of money which would be pretty light, but you would still be adding a bunch of weight to the car which would drastically reduce your track performance. If you want to go electric i would convert a seperate SUV or truck and use that to tow the car on a car-trailer. That way you will still have decent performance when you get on the track.