This is one Barry and I have.
http://cgi.ebay.com.au/SILENT-INVERT...item414a605e39
They go for around $600-650 on ebay. Has worked faultlessly since we bought it. Has no trouble with 3 computers, 3 lights, 2 telescopes and toaster all together.
A bit heavy (26kgs), but it has lasts about 15hrs on a tank for us, and there always plenty of power to share around.
Ands yes it is quite enough for a star party, we ran it for 3days at the SPSP and every month at ASNSWs Wiruna site without complaints.