Mine still plays music channels, etc., and makes a good dish mover. I'd say $50 would be quite reasonable if it's in good condition. If you buy it, it's better if you update the maps & internal battery, and there is no indication that has been done on this one (it still has the VC2 module in it, and the post doesn't say it's got a new battery).
Regardless of the price, if you decide you are interested, plug it in before buying and compare the unit ID on the sticker on the back of the 922, to what it shows on the screen line B (options-6-5 using the remote). If it doesn't match, the battery has gone dead and wiped out the UID, and yeah $5 would be reasonable because you can't reprogram that.
(options-6-5 screen line A shows the Unit-ID in hexadecimal, Line B shows it in decimal format which is what the sticker usually has printed on the back of 922s)
The 4DTV is the only thing that's worth anything.It's a Motorola so the battery is probably still good and even if it is dead the unit still can be made useful,just not subscribable.A new battery and a MapMaster job (if it has completely lost it's memory) would get you a dish mover and whatever "free" DCII is up there,notably DMX and Music Choice,plus other stuff.If the seller can prove the ID/battery is still good I'd go up to $50,but the battery should still be changed anyway.I can and have done the battery and MapMaster stuff myself,so your mileage may vary .