My personal recommendation:
Get the best boots you can afford. I've learned throughout the years, you get what you pay for, and this holds true when it comes to motorcycling. If you have $100 to spend, buy the best boots your $100 can get you. If you've got $1000, buy the best boots your $1000 can get you (I'm exaggerating on this one to drive the point home.) The bottom line is that motorcycling is an expensive hobby. Spend only what your piggy bank allows.
For the long term, I would personally get a pair of boots as opposed to something that covers up the ankle. (Ask CharlieH. He can tell you all about it.

) If and when you are ready to get something nicer (i.e. Sidis or Dainese etc.) sell your old pair to a student at PRS or here on RS. Worst case scenario - you have a pair of backup boots.