I now have 12 functioning DSR-550s. Thank you e-bay my holiday shopping is done.
As Ilya pointed out make sure or confirm with the seller that the STB does indeed function for OTA. I've seen people win new unactivated ones still sealed in their box. To add insult to injury these are going for more than the used ones (of course the used ones are more valuable). I've also seen sellers that say, "I've heard it works for OTA", "I don't know anything about these boxes." Stay away from all those and also stay away from ones that have glitzy pages as these tend to be former VOOM dealers or 2 bit sellers.
The craziest listings I have seen are ones that tell you to call your cable company to activate programming and ones that actually give information on how to subscribe to VOOM and how great the VOOM service is!!!!
If it says some thing like "I used this unit until VOOM went dark and still received locals when I unpluged it" then snatch that sucker.
In other observations the price going for the STBs are going up rather steady. Two weeks ago they were going for $15-$25, last week $35-$45, and this week they are now going for as high as $65. The number of listed STBs available have also been going down the past few weeks.