You can get a lot more for a super of comb honey, than extracted, but there are some considerations. First off, you will have to use either special setups like something for Ross Rounds, bee-o-pac or other comb honey systems.
Another option, and the one I use is putting cut comb foundation in regular super frames. It's a thinner foundation and has no wires. Getting bees to quickly fill a super comb honey takes fairly good management. You want a continuous nectar flow and a fairly crowded hive so bees will fill and cap fairly quickly. You want limited traffic on the comb to remain nice and clean. It's a balance between having the flow,bee population, good conditions, and keeping the hive from swarming.
Another option would be having a top bar hive, with all naturally made comb.
So, once you get this nice comb honey, you don't have drawn out frames that you can put back in the hive to have filled again. You have to start with new foundation. Consider that the bees will have to draw new foundation, which takes a lot of effort and resource.
You also need a market for comb honey. My first year with comb honey, I could hardly sell any. I ended up giving away sample packs to people who bought 5 or more pounds. The second time I tried it I had found a different market and those people were eager to buy and I sold out with no problem at around $4 for a 4-5 oz container.

Any suggestions on where to buy Ross Rounds? How do people think it compares to a T-Bar hive?

Below is a link to ross rounds. A Top bar hive is a totally different method of beekeeping. You can find lots of information here
http://beesource.com/forums/forumdisplay.php?f=254

Here is a link that might be useful: http://www.rossrounds.com/

I have never been able to get a price for comb honey high enough to justify the additional trouble and expense... and I sell at an organic farmer's market.

I had no comb honey at all to sell last year, but I'll try try again, this time with Ross Rounds. But not in a big volume.

Bees have to eat extra honey to produce wax. Depending on who you ask, but it takes 6 to 8 pounds of honey to make a pound of wax. If you are selling comb honey you best be getting a good price for it. I have never sold comb honey for a profit when considering my time involved and loss of honey production.

Have you tried using Ross Rounds Islandman?

I had a couple of supers set up with Ross rounds years ago and liked them for the novelty. I never tried to market them. They were for personal use, gifts and free samples. After some time I switched out to shallow supers with 100% wax foundations. Then I would chunk the comb and add to pint jars topped with honey. Simpler.