A local "gunsmith" that I've done business with offers this very service. He offers a number of basic gunsmithing services, nothing too involved, but the one service that is requested most often, the one that generates more revenue than any other service (except for interstate transfers), is cleaning and lubing people's guns. And of course, he has an FFL. He does a ton of transfers from his home, but he got the idea to offer this service to his customers because apparently some of them voiced the idea and requested it.
Remember that only 10% of gun owners are as interested or active in this hobby/sport as a lot of us feel we are. Most all of the members here at THR are probably in that 10%. The other 90% of gun owners don't care to clean and lube their guns because they don't really shoot much. I know, all the gun owners that I'm related to are exactly like that.