I got sucked into this situation a couple or three times. First round was with Lafayette Electronics in the 70's, not at all high-end but we did sell audio & car stereo. It was part time low paying & didn't last very long.
Second round was with The Shoppe, again part time (you really need a day job too if you're in this business) but this was a lot more fun. I mostly did the repair bench work but did assist on the sales floor occasionally. I was paid "in equipment" and managed to assemble what turned out to be the most musical sounding rig that I've ever had. The foundation of that system was beautiful classic Luxman Ultimate Series componentry. We used to bring prospective customers over to my house & wow them there; they almost always bought after one of those demo's although the equipment they chose rarely even resembled what they had heard. Then I would go the the customers' houses & show them how to connect everything together; some became steady clients on the side. The store manager & I were (still are) good friends, but the owner took advantage of us too many times & lost us both.
Third round was again a brief stint, this time at Music In Motion, a southern Chicago area car audio shop that sold & installed some pretty decent equipment. I met the owner at CES & later arranged a job there for my manager friend. The place was also a lot of fun to be involved with but there was no money in it for us as underlings. I assisted the installers occasionally when they needed technical expertise; sort of like an in-house consultant. Compensation was again in equipment, so I built a mobile rig in my truck that took first place at the car wars. I really hurt my hearing with that setup; it measured out >130dB SPL before clipping. We both left the place when the owner's coke abuse became incorrigible, but it was a good time while it lasted.