May I step in?
Developing any old crap domain may get your reg fee back, but is it worth the time invested? Unless development shows significant earnings (or at least minimum hourly wage), I don't see the point of earning my reg fee back at the cost of my time. To me, that's like doubling down on a bad hand. I'm thinking the mini-site king can build a site, stock it with content, and throw up some affiliate ads in minutes. That makes a difference. However, if you're like me, even the ugliest little site will take an hour. As in $7 an hour.
And Sidd, so far as buying a $500 name.... If you can't even buy a decent $7 reg, I'd tell you to keep your wallet in your pocket when looking at the $500 names. Yes, in theory, one name is better than 50 names. In practice, though, you need to learn much more before your can choose that one name. With 50, you might get lucky on a couple. With one, if you miss, it's game over for you.
I agree with RTM that there are good regs out there. One reg can flip for 20-30 times your investment quite easily, while you might be pressed to double an investment on one $500 name.
What to do? Take your mistakes, print them out, and hang them near your desk to remind you to be cautious. We all get tempted by completely stupid names, just because they appeal to us on an emotional level. It's sometimes hard to maintain focus, which is the only way to make money in this game. Trying to save face or a few bucks by dressing up your mistakes is what I call losing focus. Eat your loss, and remember to stay on target.
If you are unsure what to buy, you could always go over freshly dropped domains. Most of them stink, but there are some winners. And you know that at least one other person in the world thought the name was good enough to register.
Set a budget, keep your expenses low, and try to sell names to pay for the new ones you buy. It's too easy to get way ahead of yourself buying before you know what to buy. There is a learning curve, so just assume most of the names you at the beginning like are crap.
It's like a poker game. I can't tell you just to sit and watch, but don't bet. So buy some names, but really control your funds until you see you're starting to come out ahead.