I have this one holds a decent amount and not big and bulky http://www.chaparral-racing.com/Product/nelson-rigg-mini-magnetic-tank-bag/204-CL300.aspx?source=googlebase&gclid=CNvI7I7urqsCFTMBQAodi2vEIw
Electricians don't come cheap.... well at least not the good ones Another option is running the line yourself and having an electrician make the connections if your not comfortable making them this should save you some cash.
If you rewired your basement you should have no trouble. If you have to run through conduit I would suggest you use single strand it's much easier to feed through and yes GFI is a must.
You guys need to chill with posting up rules and regulations before the list of riders dwindles to 0. Save the safety lecture for the pre-ride meeting.