You say its in good shape but the words means little. Its VERY important that a prospective buyer is able to inspect it filled, up to temp and running. You’ll find many of us here tell people not to even think about buying a used spa unless they can see it fully operational no matter what it looks like or what promises are made. That will go a long way toward selling it. I would fill it and retake the picture with it full and mention in the ad that it is "fully operational and ready for your inspection".
While “Condition” is the #1 thing on older spas and that is a good brand known to hold up well over time, $2k is a little high being a 10 year old spa but "$2k OBO" as you have listed may entice people to check it out but they’ll want to bargain. The wrap around "decking" may be enticing to some people but I'm not sure it adds too much value though it may help move it. I think you need to be ready to take the “OBO” part seriously. Plus, moving a spa can be a pain for the buyer so keep this in mind if you get an offer like "$1200 and we'll take it away tomorrow".
Craigslist is a place where you'll get the most eyeballs looking at it. I'd give that a shot.
