Nick, I've got a Werther 3.
Noise levels are relatively low, it has an internal 0.8L storage tank, it is a piston rather than a diaphragm type so no pulsing, and it cost me a £100.
I've had mine about 6 months and it's been fine, apart from me dropping it off a table and mashing up the internal chassis. However having super glued it all back together again, it's been fine ever since.
Try the link below:
www.maywoodgroup.co.uk/Compressors/SearchResult.aspx?categoryID=15
Karl