That's a pretty fair estimate, and that's assuming you get the leaks figured out, so you can advertise as 'no leaks'. I also assume you're talking about air leaks, not water leaks. Air leaks can be tough to find. One way is to fill the tubes with air, and then sponge soapy water on the tubes...watch for bubbles. If that doesn't work, try putting a little glycerin in the water (makes better bubbles). Anywhere you see a bubble, mark with a crayon, or some other marker that you can later wipe off.

I recently sold a 10' Avon rigid hull for $400, and it sold in a day, so that was a little under-priced...........

...you could try asking $600 once it's clean and no leaks, have it fully inflated when folks look at it, and take a lower offer if you're motivated. Also, maybe advertise it a couple weeks before lowland lakes trout opening.

good luck.