It's understandable, but it wouldn't be heard in normal conversation, or ever for that matter. The proper way to say this is 'It doesn't matter what the price is.' This is if you've already brought up the gift in conversation. If not you would phrase it 'It doesn't matter how much the present cost(s).' At a stretch you could also get away with 'It doesn't matter what the price of the present is.' but this doesn't make as much sense grammatically i don't think.