depends on the wattage that you need, but dc-ac inverters are available at all auto parts stores, just check the labels on your gear, add up the wattage, and you know what to get. deep cycle marine batteries might be harder to come by, i know west marine sells them in the U.S. but im not sure about canada

edit: the inverter would be something along these lines :
http://www.dcacpowerinverters.com/itemdesc.asp?ic=ML1500-24

I used a 1000 watt inverter this summer while camping hooked up to the truck and it worked just fine, powered 2 cdj's and xone 62, as well as 2 powered monitors. Would'nt run the sub with all that though, should have got the 1500 watt. Some guys near our camp were using and re-charging car batteries which seemed to work just fine also.

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car batteries are good, but the reason i keep saying deep cycle marine batteries is they are actually designed to run for long periods of time, if you use a car battery you will severely shorten the life span of the battery.