The age concerns me a bit, especially when it comes to getting either serviced. I'm wondering if the money cost to service with parts would be better spent towards a new regulator set up? I am not a DIY service person.
I was hoping they were newer, but given the age of the owners, I'm not surprised that they are 25 years old.
Getting a deal on a fairly contemporary used regulator set can be as easy as looking up an aggressive new price (Leisure Pro for instance) subtracting an agressive service visit and enough to mitigate your risk and the fact that you are buying used / without warranty. Once you look at doing so on a 25 year old unit even $75 is generous. Without wanting to sound crass, this is a real lowball situation.
I have nothing bad to say about USD but our Sherwood gear has served us very well.
If you have the means I'd say no thanks and move on.
You have a very good chance of scoring a great deal on a late model used BC. Watch Craigslist for lead too.
Pete