I bought this one from Mad Vapes, it's a SLB knockoff but it works just fine, has the manual mega
batteries which last a lot longer for me and a car charger also. Basically you get 2 complete mega 510's, 5 carts, charger and car charger, plus Mark always gives you an extra goodie with your order and has great customer service. He's out of them right now but he should have some more in soon. Also 60 day warranty on the batteries.
510 Mega Kit with no Box
If you want the genuine cignot does have the best price.