Accessories that are a disaster waiting to happen can bankrupt a dealer. The distributors I contracted to were -strongly- advised to not sell individual components to customers. No regulators, no starter solenoids, no battery combiners. one warranty -consideration-, eats profits like crazy. Time is money and arguing with a customer who sports a block of wood for a head is a good way to lose your butt. Customer claims a warranty on a "bad" alternator - which tests to spec fully loaded on a test bench, we told the customer to bring the car in and for the nominal checkout fee we would tell him what the problem really is.
Manufacturers are caught in a grand trap deciding between price and quality. I realized this back in the eighties when I built Quicksilver. Shooting closed cell foam onto water tanks was not cheap, nor was running electrical conduit tubing and Klixon marine circuit breakers. I chose ThinLite 48" fluorescent fixtures because I could buy 48" tubes by the box cheaper thn the 18" tubes which turned black every other month.
Finding a Service Dept. that cares whether you live or die is crucial. They'll go to bat for you and help resolve vendor issues. When Sal at Kool Fun, Inwindale, CA. (they rebuilt, and manufactured gas refrigerators) told me RV gas refrigerators are (expletive deleted) that changed my mind. Forever. Sal also told me electronic water heaters were fits in the electronics dept, I chose a 10-gallon manual for Quicksilver. I've got better things to do than fight warranty issues over garbage grade stuff.
