Cost for my tower so far:
Rohn AX40, already disassembled w/ unused "dirt drum" base - $125 on craigslist, 40 miles away
Rustoleum Rusty Metal Primer (galvanization was mostly gone) - $13
Rustoleum Smoke Gray Paint - $38
Acetone - $5
1/8" wall, 1.25" OD DOM tubing (fabbing concrete legs) - ~$40
6 pack of 312 Wheat beer (welder payment, I didn't trust myself enough) - $7.99
4x4x3' hole - Free, I dug it myself
Remesh & Rebar - ~$30
What's left to do:
Dig the hole out a little bit more
Weld L-brackets to tower legs, buy some threaded rod and instant concrete. Dig some small holes, put the threaded rods in the 3 small holes of concrete. Run the rod through the L-brackets. Use two nuts on each bracket to adjust tower for plumb. 
Fabricate a wood frame around the hole
Get concrete delivered
Fabricate a simple clamp-on gin pole
Wait 30 days while the concrete is setting
Assemble tower
I haven't quite decided on antennas or coax yet. I think I'm going to be running a 3-element 10m yagi, my 5-el 2m yagi (vertical) offset 1/4 wl from the mast, and probably a Diamond X30A dual-band at the top. If I can find a nice length of Heliax LDF4-50A for the top vertical, I'll use that. If not, I'll use LMR400 for the whole run, rather than just the ends. The 2m and 10m yagi will be fed by LMR400.
If there's room, I'm going to put a yagi up for 13cm band so I can experiment a bit.
