Some kits are pretty poor and are fairly dangerous in the event of a shunt. Yes they are cheapish, but I think that you get what you pay for.
I want a relatively safe car, one that handles well, is engineered professionally and one that will not break the bank. Saying that £35-40k or so is not exactly pocket money!
I had bought a Caterham in kit form back in 1997. At that stage I couldn't afford a Cobra replica. However, the Caterham did not disappoint, especially when the 1600cc engine I fettled produced 204 bhp at the rear wheels, just over 400 bhp per tonne. So the bhp of the Cobra may be a little lower at the wheels, but the torque will be way up and that is what makes them very driveable.
So now I need to decide if I want such a project and if so which spec. of car to go with.