If your talking about inflating tubes and such, I have had a cheap Coleman rechargeable that works great! I have had it going on 4 or 5 years now and it even stays out at the island over the winter. Charges right up in the spring without issue and the battery lasts a long time. I think I paid less than $30.00 for it too!! If it died tomorrow I would buy another in a heartbeat. I also carry a plastic hand pump in case I had to top off for pressure but so far the Coleman has worked just fine. It also works great for deflating!!
I think messing with an inverter would be a pain.
Edited to add, this is very similar to the one I have except mine is green and has a separate charger (older version of this maybe??)...
http://smile.amazon.com/Coleman-Rech...n+air+inflator
Edited to add, looks like they have a 12 volt version too!
http://www.amazon.com/Coleman-200001...CGB31NXEPD83CF
Dan