Its worth what someone is willing to pay
If it is in great shape besides the factory patches, and doesn't look like it has been stored outside in the sun, isn't moldy, etc. I personally would be willling to pay upwards of near $1000 for the boat alone. Make sure to open up the zippers and have a look inside at the bladders and zipper condition.
I got an 8 year old air lynx II in great shape last year for $550 and thought I got a great deal. I would think a 10 year old super puma in very good shape should be worth twice that or so.