Well the pattern is kinda tight....

(9)Altec horn 299-8AT driver will consider sell1@a time - eBay (item 280571540159 end time Oct-15-10 18:32:34 PDT)

This guy, has issues. Seems to be a nice enough fellow but thinks he is sitting on a gold mine. he isn't. A fair price for these is about 700-750 a pair, and that is what I would offer. About 650 for drivers, and 100 for the big horns that often have to be given away.

He has a few with 290-4G.

If you buy those don't pay a lot. The horns have little resale, and shipping is gonna be rough.