I like the following two:
aero-dynamic.com -- very nice, hyphen is fine, this could make a great product site for a manufacturer of "aero" products -- I can think of wheels, triathlon equipment, and of course vehicles and other crafts as well. HINTS: try companies with the word "aero" in their name, logo or motto. I do like this one.
aeroplane.org --this worldplay to airplane is very catchy and brandable (but check TM database to clear it)
As far as $$, it's hard to tell but with the right client maybe even $$$, ya never know. Aeroplane.org is much less.