Boards are weight specific. Height has almost nothing to do with selecting a board. In fact, if a shop is going by height in recommending a board, turn around and walk out, because you already know more than they do.
I would say you are boarder line on wanting to own. Rental prices do add up and probably for the cost you could have your own equipment. If you buy, make sure you do not spare any expense on boots (if you don't already own), that is the number one thing to not skimp on.