What would be a good beginner's cube?
Some people say go for an intermediate cube, like a ShengShou Wind. Personally, I went straight from Rubik's brand to a Guhong 2, and had no problems. I guess you'd struggle if you went from a Rubik's to a Weilong, which is a new cube that can be hard to control.
I'd recommend a Guhong 2. I feel it's a little easier to control than some 'faster' cubes (pretty sure Alex (5BLD) uses one, and has sub-8 global average with it, so it's not slow). I wouldn't go straight for a Zhanchi/Weilong/Shuang Ren, but the Guhong's just a little more solid, IMHO. So Guhong or SS Wind.
where would be the best place to buy it from? I live in the west coast
Best?
Quickest, for you, would be TheCubicle.us. They're based near NY (I think Phil moved in the last 12 months, feel free to correct me anyone). If you don't mind waiting a couple of weeks, you could go with the
cheapest option, which would be one of the Chinese/Hong-Kong based stores such as HKNowStore, Lightake, Fasttech, Wallbuys, etc..
TheCubicle are very good. Great service, and the best stickers money can buy. If you're not worried about chasing the best price, and/or time is a factor, would definitely recommend them very highly.