Well, before spending the $170 in parts for the DYI Vagabond posted on myJTP.com's youtube channel. I always wondered why I couldn't just use my computer's UPS. It's 725VA, self contained, built in charger, really cheap (<$100) why wouldn't this work? Well I got some time to do some testing and found out the following. Using my Photogenic 600ws monolights I was able to get 125 full power pops off of my fully charged UPS (battery in the UPS was about 2years old) til it cut power when the battery reached about 19% charge. Recharge time on the strobe was about 3.5 seconds, so not really as fast as pluging into a good 'ol AC outlet. Not really enough for a full shoot but I could do in a pinch. The battery in the unit is about 1/3 the size as the one in the Vagabond, so that explains why it didn't last that long.
So it worked but there is alot of chatter on the flickr groups about the need for a pure sine inverter to power strobes. I believe my strobes have a transformer rectified front end that charges the capacitor bank which is the worst ones to run off a approximate-sine inverter like my UPS - I didn't fry anything in the process, and nothing even got too hot in the process, but I think to be safe, I'll build the DYI kit with a pure sine.