Honestly I am not so sure but I will try. Problem is that a lot of my additional expense came from stocking up on things every time I thought I had it nailed (mega attys, 306 and drip tips, batteries, etc)
Initial 808 kit and extra cartos, initial eGo kit, 510 attys, 510 LR attys, 306 attys, 306 LR attys, drip tips, eGo Mega cyclinder attys, eGo LR cylinder attys, eGo tanks attys, extra eGo batteries - probably around $600-$700 or so. I could be way off, it might be as low as $400-500. Also could be as high as $1000, but I doubt it. Keep in mind I did stock up on some things. Not crazy quantities but I never bought just 1 or 2 of anything and I still HAVE virtually all of this stuff...except for 1 eGo battery that died and the various assortment of attys that have died. Truth is I probably have enough 510 and 808 hardware to finish out this year, for sure, without any real worry.
GoGo for the same time period, assuming cartos last the way I have seen, and NO additional batteries would likely be something like $60 for the initial kit + $192 for cartos (assuming using and tossing 2 cartos/week for 8 months at $3/carto). And my experience so far does not suggest that you would need 2 cartos per week, but this leaves a little fudge factor in there.
Again, this was just a swag. I don't have the heart to actually go and add it up.
Dormouse makes a GREAT point about parts availability for your ONLY PV. I guess all you could do is to spend a week with GoGo and if you like it go back and order 20-30 cartos...like I did.