Bzzzzzzzz . . . Bzzz . . . Bzzzz
From my reading of alt.home.repair over the past year, opinions are strong and mixed. The consensus of the group is negative on low priced airless sprayers but, clearly, everybody doesn't think so. There does seem to be general agreement you have to thin latex paint. Campbell Hausfeld seems to get somewhat better words than Wagner, but I don't know if that's for low end sprayers. Also, this could be the "Mine's different, so it's better," phenomenon that used to be the hallmark of Volkswagen bug owners. :-)
I owned an $80 Wagner about 10 years ago. It dripped paint everywhere, and you could paint for an hour and clean-up for two. I threw it away -- I wasn't willing to risk losing a friend by giving it away.
Sorry if this doesn't give a clear answer. I added it because it's a common question.