From my understanding, they didn't hold very much, and there are certainly other choices on the market that work equally well.
The incubator they're advertising right now is a Hovabator with some supplies. You will probably want to add a proportional thermostat to that, otherwise you'll be fiddling with it all season, and that's nerve-wracking. That said, I use Hovabators, and they are fantastic, so long as you have a proper thermostat.
The other incubator is mini-fridge/warmer originally designed for offices and truckers, but rebranded for use as a reptile incubator. Folks began using the original fridge/warmer and found it to hold temperatures decently, so someone managed to get a deal to sell it for that purpose. The original was first seen for sale on ThinkGeek, but they don't appear to have it any longer. (ThermoKool Deluxe Mini Fridge/Warmer). There are a lot of similar fridge/warmers on the market now, since that one came out. It might be worth testing some of them to find out what sort of job they do at keeping stable temperatures, to see if there are any more options on the market now.
Those who have this incubator (or the orignal mini-fridge) will note the suspiciously familiar design seen here in a brighter color: http://www.amazon.com/WHITE-FOX-Comp...697367&sr=8-52
The big cabinet incubator is a poultry egg incubator (many of which can be used for reptile eggs, so long as you use sealed containers), but they do have it at a very good price.