There are quite few inflatable foils out there as well as the PL ones you mention.
A few foil makers such as Advance and Windtools make them as do some of the windsurf manufacturers such as GUN.
Take a trawl through some classifieds sites and see what you can find, then ask back here when you've found a few within your budget.
If you're based in the UK then try
http://www.forces-of-nature.co.uk/ads_frames.htm for some classifieds (its my site and I know that I added a Waterfoil to it just the other day).
You may get some more localised help in th forums there too.