I have had a couple. They are OK at best. The guns are not well made, and the ejectors will eventually go bad.
I sold one for $125 that was in good shape, mounts included. (Clip-fed) The other I sold to 3DNWV on this forum that had ejector problems and was in OK shape for $50. (Tubular magazine fed)
With the 17HMR and .204 gaining popularity, I don't believe that they will ever be overly valuable...but who knows?
Buy the conversion kit....make them centerfire.....reload the shells....and kill some varmints!
The shells run about $.50 to $.75 apiece. That's a little pricey for what you are getting. They are flat and fast, though!