I'm still brewing extract batches and I usually just order a kit from either MoreBeer or Northern Brewer. The beer I'm drinking as I type this is a 70/- from a NB kit. If you go with that kit (or any, I suppose) just be sure to check the amount of priming sugar you use when bottling. Most of the suppliers send out a stock amount of priming sugar and even cutting back a bit, my 70/- is over-carbonated, in my opinion. I'll be using half the provided amount when I bottle my stout next weekend.
Cheers!