Back during the Dark Ages, I saw Joons valks going for hundreds of dollars, sometimes even the ones that were colored all funky, but this was because there was really NOTHING Macross-related available mainstream. Your choices were really limited. Also, seeing as how 1/48s are pretty expensive now, I'd be surprised if they went for thousands the way the old Taka's and Bandai's used to.
Then again, if the Macross well dries up, who knows what could happen?