Assuming they're in reasonable condition (expect nicks, scratches, scuffs, etc, but no major gouges), and they come with working valves, I would say that's a good price, especially considering all are still within their 15-year lifespan. That means they can still be hydro-tested, and 1) the user will have a high confidence that it's a safe tank, and 2) they can be filled at commercial shops, if desired. What size are they (as in, are they rated at 30, 45 or 60 minute)?
If new valves are needed, and an SCBA fitting is desired (as opposed to DIN300), one of the members here (Jerry? I can't recall his user name) has posted in the past that he might be able to get a refurbished valve for under $40.