Just get the best speed cube you can right away.
The faster you get, the more you rely on things you can do subconsciously. One of those things is your hand movement. Don't waste your time learning to deal with the flaws of a bad cube when you could be learning to control the advantages of a better one.
As far as which cube to get, in my experience the Zhanchi, Guhong v1/v2, and Lingyun v2 are all equal in performance but different in feel. I prefer the feel of the Guhong v2, but you can't go wrong with any of those. Search this forum for lubricant and modding discussions. Look into Z stickers (51morefun.com), MODstickers (thecubicle.us), and Cube Smith (cubesmith.com) for better colors than the stock ones. If you want to purchase your cube, lube, and stickers all at once with free shipping over a certain amounts (depends where you are), thecubicle.us is a good choice.