If you look on the stern of each hull (where the rudders go), you'll find a series of numbers and letters (should be the same for each hull, but may not be). It might take some washing for the numbers to show. But with the serial number, we can identify the age of the boat. Also, tap the hulls on both sides every foot or so. They should sound the same, and a soft, squishy sound indicates a hull problem in that location.
The sail number does provide some indication of age, combined with the color(s) and pattern of the colors. Different sail patterns were sold in different years, and some sail patterns are more desirable then others. Very roughly guessing the sail number seems to have been from around 1979.
What is the condition of the sails and mast? It seems like it would be more likely to sell as a parts boat, rather then as used. And location matters a lot. Shipping the mast and/or hulls is expensive, and would begin to quickly exceed the value of them. I'm saying this because you're saying that you don't live anywhere near water. The same Hobie 16 in Florida or California is worth a lot more then it would be in Colorado.
Eight hundred seems high, but it really depends on things.
Best of luck,