thinking about kegging

I just stumbled on a 20# co2 tank on craigs list for $50. I figured I might as well go ahead and grab this one, b/c it may be a while until this type of deal comes along around where I live again.
It may be a while still until I get the rest of my kegging equip depending on the prices I can find. Have you guys found it cheaper to go ahead and buy a system with everything in it, or piece it together yourself. It seems the regulator could be the most expensive piece I need? Can I just pick one up locally for cheaper maybe?

Check out keg cowboys site from what if seen he has the cheapest setups.

I found it cheaper to be patient and keep trolling sites like craigslist/kijiji for the stuff and piece it all together. Local shops charge alot around here. Of course online sites in the US have very decent prices....but shipping and fees kill any deals for us north of the border.