Personally I would've gotten an 88 key.
I used to own a 70 key, but all of the songs I wanted to play were not on the keyboard, so I just wallowed in my depression.
But there are some great weighted key keyboards which are very cheap and sound and feel like the real thing.
What I have is a yamaha p95, it sounds great (better than some pianos) and it comes full with 88 weighted keys, a pedal, and a double x stand. But I'm not sure if they have the same deal in other music stores.
It was only 500+ all together which is pretty good.