I'm mostly in to the classics and I've seen a few Tempest sell at auction. They are probably in the top 10 as most desirable. Keep in mind they use a vector monitor, so that alone can be pricey. A fixer-upper would be arond $700 to $1000 provided everything is there and working. A friend of mine had a busted one and was still able to get a good amount of cash for it on ebay.