This was Schwinn's last attempt (and a poor one at that) to build a half-decent BMX bike. But they were built with old technology and were just as heavy, if not more so, than the Sting-Rays. I used to have a stripped-out 1987 Predator Freeform EX that sat in my parts lot for quite some time. I was going to take to the scrapyard, but some poor sucker actually saved it at the last minute.
If they are in dead mint condition, you can probably get around $100 on eBay for it. Of course, I haven't checked for quite some time so that info may be out of date. If you are buying it to restore or flip, run far away. I would only buy one if I truely wanted it.