Yup, if it's printing well it's a steal, go for it. If you're able to see it in person as to see it in operation, take some of YOUR own sample files to print, and make sure you see it run a few test draws. If all nozzles are firing and there is no significant nozzle deflection take the deal and don't look back.
Be aware, while they're still workhorses, if it's not printing perfectly, it may not be a good deal, especially if you're not inclined to do your own maintenance. A head for the JV3 will set you back around $1500+ for OEM parts plus installation labor, and it has 4 heads. So if it's in need of one head replacement, the deal's not as good. If it needs 2 or more heads, it's not much of a deal at all.
That said, even though it's an older machine, they were built extremely well and are serious workhorses. You cannot go wrong with one if the price is right and it doesn't need an overhaul.