I got one off eBay for £15 + vat, same gun but different hopper.
We use it for applying, as rigs said, micro, R10/R7 and hope that thinly mixed rend-aid will go through, you need a good compressor though, I just bought the LK402 which I hook the 15m ritmo air line into and spray constantly, no stopping to allow cylinders to fill up, probably do 2/3m a minute very accurately.
If you test a top coat through it, please let us know how you get on Bobby, me and rigsby are going to test it when we both have a few hours spare, hoping it will save on buying the more expensive option.