Here's another cheap cleaning/repair stand. Basically just two lengths of 2x4, cut and glued/nailed together, bolted down to the workbench with long 5/16" bolts. A hole of somewhat larger diameter than your fattest downtube is drilled in the hinged end as shown. Standard wood working clamp holds the bike snug in place.

The 2x4 on the right side has a bevel cut along the length that sits on the work bench, so you can mount it tilted on the work bench, or flat. First photo is just the stand, bolted in the flat position, second photo shows it in use in the tilted position. You can see a line on the end of the right side 2x4 that shows the bevel angle I cut it along the bottom, except for the last 6" or so. (Click photos to enlarge)

Pros:
Cheap
Rock solid
Takes most any size tube, depending on how much you want to pad around it

Cons:
Limited choice of tilt angles
No height adjustment
Obv., you need to already have a workbench

Next time I find myself with a scrap 2x4 in the right length, I'll probably build one that tilts the other way, so I can angle it both ways. Had I planned ahead, I could have made this one a double-ender, with just the addition of another hinge.