Wow, very nice tank! I might have to get a 12g long myself some time.
Bought at manzanita.com. They were awesome. I called them up and told them what I was looking for. The guy I talked with went out into the warehouse and picked through the ones that he thought would fit, and gave me the stock number to look at on the site. For a few extra $ he threw in a few extra "sticks" that I could use to complement the stump.
Ah, I had a slightly different experience from them =/ Emailed and called them and they told me that they'd update their site with the stumps. When they did, they were all too big so I tried getting in contact with them again (voice mail and email) but they didn't respond. So I ended up doing a rock scape (which I'm satisfied with, but your stump makes me jealous
). Maybe I'll try again when I set up my nano.