The idea of a kitbash is to take an existing product and modify it a bit, then let the guys who made the original resell your modified piece so everyone can use it. Clearly people don't do it for money, since they don't get paid. I guess it's the warm fuzzy feeling that other people are using something you created.
I am into the process because it's not THAT much more work to share modifications than it is to make them for my own use. I bought the Harbormaster set in order to make more buildings with a variety of textures -- the Thoumont's set is great, but it's nice to make buildings look at least a little different.
So, I went through the trouble of making a bunch of floor tiles, walls and posts. I've got a LOT of pages of stuff. But, the idea of a kitbash is that it's fairly small - only a couple pages each. So rather than pretend I'll complete a total conversion of the set (I'll leave that to the pros!) I opted to polish up the floor tiles and submit just them as a kitbash.
Here's a sample tile.
Wouldn't you know it - the file I ended up trying to submit is over 40MB, and comcast won't let me email it. Sigh. Time to see if the folks at WorldWorksGames would like me to send it some other way...
[Edit: It turns out I had exported the PDF file as lossless, rather than compressed. I set it to be compressed, and it was reduced to a little over 5MB.]