Triplebogey, take a look at this site. They offer a guide to building your own putting green. However, it's not as expensive as you think. The only thing you will need is a reel mower, since typical mowers cut the grass sideways and wouldn't be able to cut it down that low. $700 should be plenty if you were going to go through with it. I'm sure you could find a decent reel mower fairly cheap.

http://www.putting-greens.com/

Hope this is of some help.