this came up a while ago.
I think vomitron was the one having this problem.

If i remember correctly, you can get velocity aeroheads in 24" from aebike. for about $44. in 28 and 36 hole drillings
http://aebike.com/site/page.cfm?Page...and=453&type=T

and I think sun also makes a 24" rim. the ME-14A.
I only know of a canadian site that sells them in 28H