<< Any ideas on an inexpensive sprayer? >>
Some ideas that may help:
The rheology of latex paints requires considerable power to push them through
a nozzle. That's why companies like Graco make well regarded (but pricey)
airless sprayers. The Wagner units do work but you can tell from posts in this
NG that there are many unhappy users, too.
Your best recourse is probably to plan on using oil based paints, and doing
your work outdoors. There are lots of $30 spray guns that work just fine if you
thin the paint correctly (assuming you already have an air compressor). Some of
these low cost spray guns may have a pressure feed capability and could handle
latex paints with heads up experimentation. Watch the compressor pressures so
you don't turn the paint cup into a round bottom ball. Good luck.