Around $10 US for the rba base. Also joyetech is sending me something called the rba Base 510 adapter which allows you to read the ohms when building. I am not sure if this will come with the standard RBA base kit or if it will be an additional cost added separately. Hopefully I will have more details soon.
Made me look.
If you weren't aware, a lot of these coils have 510 threading - like all the Kanger BCC stuff. You can actually screw a 510 atty into a PT, EVOD or MT3s base. Not that it will do you much good - it will never make a center post connection. But I still use that bit of info to stand things like 306 or 510 attys upright in a T3s base when plonking them in simmering water to clean. Gets a nice percolation action going that way. Water just sploots right out the top.
So... the eGrip coils screw into a Kanger base just fine. But... they won't make electrical contact - the center post on the eGrip coil is too short. It's a lot shorter than the center post on a Kanger coil. It was worth a shot to see if a Kanger base could be used to get the RBA onto an ohm tester, but it doesn't look that is gonna work if the RBA base is anything like a coil bottom. Will need that adapter from Joyetech to do ohm checks.
At least I know what I'm gonna use to clean an eGrip coil now.