Most of the time I don't even wear shoes, I wear "flip flops" or go bare foot! Some times I wear climbing shoes about an inch smaller than my foot! I am really serious about thinking about foot wear, and its use. First and foremost I am a climber, I take great care with my climbing shoes, and their choice. Some times when I am guiding, and give the normal advice of "push up on that foot hold" I really wonder how they can-because their shoes are just not up to it.
There's a video of Ondra the genius, trying to climb a 7a slab in boxing gloves somewhere on the net, but the same applies to foot ware. It has to fit your foot, and be fit for the purpose, there are only a few good makes, I happen to work for one of the best, so I am biased, but my advice is good. There is no bit of kit that effects your climbing like your shoe. Don't get a good shoe, get the best one you can for your foot, and objectives, and keep the rubber clean! Save money on anything else.
A good shoe costs a good bit more than an ordinary one, but the difference in quality of enjoyment is immense. The difference in diving fins price is astronomical, believe me I know the difference. We are lucky with climbing shoes. You cannot learn good technique with bad shoes, you are forced to just get stronger! Getting stronger is great, but having bad technique will ultimatly limit you more.