Bought a house with Rainsoft gold unit. Are they worth anything?

Obviuosly, if they work, they are worth it. If they are not working, are they worth fixing? That is another question.

There are many Rainsoft customers on this forum;most here due to problems with the units and other difficulties. Find out if the units are working and where a service tech can be located--if locally.

If your system is a "timer" unit, I would get rid of it. Rainsoft still often sells timer softener, which are very inefficient. Their RO is very simple in design and apples-to-apples competitors may serve you well. Going new with drinking water systems is preferred, IMO.