You've got some good SEO going on with the site. The only thing I'd point out is the SearchMonster link at the top. I'd move it down towards the bottom, because the Google spiders read pages from top left to bottom right, so you want all the relevant keywords and content to show before anything else.
What kind of Click throughs are you getting? I don't have an appraisal, which is what I know you wanted. The domain name alone is reg fee, but you're intention is to get revenue, so you'll just have to wait and see what it makes and figure 12 months revenue = value.
I think it definitely has potential and as you getting better SE placement, you should see traffic and revenue increase.
I'd also add "Arthritis Prevention" to your title, as that's the domain name and may help you place better under that keyword search.
Good luck.