Turbsy: Listen to Autofly's good advice. Don't waste your money. Most airlines will look at a self bought type rating unfavorably especially if you don't have stick time in the aircraft after the rating.
With the very minimum requirements I wouldn't bet the farm on getting hired with 500 hours and a 737 type with no time behind the wheel. There's just too much competition around. Unless you happen to be the boss's son or something.
Chip away at it one step at a time. Good Luck.