Mike,
If you want to offer online reservations you either hook up with someone like FORE!, buy a few thousand dollars of their software, sign a lease with them, and then offer the service on your own course's website. Of course, your potential sales are limited by the traffic your site generates.
Or, you hook up with a company like Golfnow, barter away a tee-time a day, and have your course featured at a site with thousands upon thousands of visitors.
All it takes is a couple of months of vigilance on the club's part to keep track of how many of the rounds they've listed on Golfnow (or any other third-party site) are being sold vs. how many of the bartered rounds they've given Golfnow are being sold. If the ratio makes you happy you continue, if it doesn't you stop.
p.s I've viewed some of the offers on the GN site and compared them to offers that the same club has on their own site. I found many cases where the offers were the same, some where the club's own offering was slightly higher than what they are giving GN, and some cases where the GN offering was a lot lower than the 'special' rates posted at the club's site.