You can go two ways with this...
An mx5 with a welded diff, coilovers and a bucket seat will drift quite nicely and due to their snappy nature you'll learn far more in one than any of the larger S bodies. Clutch kicks, feinting (Scandinavian flick) etc will be far more useful to you in a low powered car, you can then use this experience eventually when going up to a more powerful car.
Perhaps consider an E36 328i, plenty of power, readily available and they'll slide all day long reliably.
I have an S14a now and it does most of the work for me, it's such an easy car to drift but I wouldn't want to jump straight into one. You're more likely to rely on the power alone and it's a bit lazy in my opinion. The main thing is seat time though, practice makes perfect.
Have fun!