As "tatest" has stated, one of the reasons that there are fewer used Jayco Class C motorhomes for sale is that Jayco produces far fewer vehicles than the "big" guys (Thor, Forest River & Winnebago) do. That being said, another reason may be that Jayco owners are satisfied owners and they do keep there motorhomes for a long time. That is certainly our case. My wife and I have been RVing for 31 years and have owned 7 motorhomes during that time. Most were kept for only 3 to 5 years but our current Jayco Greyhawk is now 11 years old and we still LOVE it.
Jayco is the only manufacturer in the business which still offers a 2 year warranty (vs the "standard" 1 year) and they do stand behind their products. We have had few problems with our motorhome but a couple were significant and Jayco fixed them for free even thought we were then out of warranty. IF they deem the problem to be due to a manufacturing defect, they will fix a problem when the motorhome is out of warranty.
We highly recommend Jayco products!