If the names are good, with little to no promotion you can still make your money back quite easily.

If the names are great, or you promote heavily and get aggressive on the selling side of things or cobranding your parked domains with your developed, then the sky is the limit.

Most of my domains are 1st registered, and many are doing outstanding, with all but a couple on track to pay for themselves w/n 6 months of registering.

For example, http://www.XELaw.com itself has earned over $100 and I've only had it 2-3 months.

-Allan