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So you ran wiring for an A-Bus system only? Or did you do it correctly and home-run the speaker wire as well?

A used Russound or Niles A-Bus system from eBay would be your best bet. Cheap, but usable. Monoprice in-ceiling speakers - use the 6.25" so the buyer can easily upgrade in the future.

Unless you plan on having the system running during any showings, I don't think you'll get much, if anything, for adding the system, assuming this is an entry/mid-level house for flipping. Noting that the house is "pre-wired" may do just as much good.

If you mean you home-run all of those, then you did good. Assuming you also ran wires from the keypad/volume location to the speaker locations, too!

If you only home-run the cat6, you've limited yourself to an A-Bus (or Digi-5) system.

If you did home-run everything, I'd just install volume controls and speakers (assuming in-ceiling), and use a stereo amp for demonstration purposes (during open house), advertise it as whole-house-audio-ready, and not invest in any system gear.

Jeff

You'll need either an impedance-matching speaker selector, or impedance-matching volume controls. There are cheap volume controls, but folks have had issues with their impedance-matching not really doing a good job.

It'll be just fine... I'd recommend a name-brand control like Xantech or Niles. Folks have not had good impedance-matching luck with the inexpensive Monoprice variety. It would certainly be better for your future buyer if the volume controls did proper impedance-matching.

Jeff