motorvation spyder value

I just bought a Moto Guzzi SP1000 for a winter project bike. It came with a Motorvation Spyder sidecar. I'm guessing the sidecar is maybe 10 years old? There is some surface rust on the mounting bars. Can anyone toss out a range of how much I could sell the sidecar for? I didn't see any direct comparisons on the Classifieds.

I plan to fix up the Guzzi, take the sidecar class from the local motorcycle safety foundation, then get my endorsement. I know what I bought it for but I would really like to know what it is worth.

TIA