Hi and welcome to the forums. You might try
looking here for price vs condition - but my personal opinion is that Argosys are becoming more popular than they have been and are fetching higher prices.
Keep in mind that repairs that need to be done - especially big ones e.g. axle replacement, water lines, appliances and body dings and paint substantially impact value.
You might watch ebay for a few weeks and see what other argosys are selling for.