For a well-designed and well-developed Theme*, $100 should be the minimum, no-support price.

For one thing, such a Theme shouldn't *need* post-installation support. It should just work as-designed. Such a Theme will properly differentiate between presentation and functionality, and will be developed to play nicely with WordPress core, as well as Plugins.

For another thing, what gets lost so often in the "what are you paying for" discussion is that you're paying for the design and development work that went into the Theme in the first place. I don't care what Richard Stallman says; the skill and effort that go into design and development have value.

Post-installation, support becomes the greatest cost, and should be priced appropriately. Support means ensuring the Theme works as-designed, and as-advertised. Support is not adding features and doing custom design/development, which should be properly differentiated and priced separately. (When people realize that quality custom development work is worth $100 an hour, suddenly that $100 base price tag for the Theme seems much more reasonable.)

Finally, the way to combat the bundle/reseller market is not via copyright, but rather via *trademark*. Just because the GPL allows a Theme to be redistributed/resold as-is doesn't mean that the person exercising that freedom gets to own or use the Theme's name/reputation. I would love to see someone take that approach: you want to resell Genesis code? Fine! It's GPL; do with it as you wish. You just can't call it "Genesis".

* Granted, I have a rather strict meaning of "well-developed", and those with design talent/skill, I'm sure, have a similarly strict meaning of "well-designed".