The coils you build yourself on an RBA will last a hec of alot longer and perform better if built decent, and the cost is penny's for cotton and Kanthal. The coil will last a long time, you just change the cotton every once in a while and burn the gunk off the coil. There are a lot of good performing RBA's for $30. Rebuilding premade coils is an option, but it looks a lot harder to me that just slapping a coil on an RBA. Well to me anyway, I didn't see the point in attempting to rebuild my Nautilus coils.
Also, if you are building a single coil on a vw mod (which most RBA's are), you don't have to worry as much about the ohms. With mechanical mods you do, but with v/w it will figure out the right voltage for the ohms on your coil. For starters you can try 8 wraps of 28ga Kanthal A1 around a 1/8" drill bit on an RBA and run it at 10-15 watts. That should put you at about 1.6 - 1.8 ohms with a decent heat capacity and heat flux. It's going to perform much better than a premade coil if the cotton wick is reasonable and not overdone.
On the other hand, if you buy coils in bulk on Ebay, they are a lot cheaper, if you want to stick to a premade coil.
Also, if you are building a single coil on a vw mod (which most RBA's are), you don't have to worry as much about the ohms. With mechanical mods you do, but with v/w it will figure out the right voltage for the ohms on your coil. For starters you can try 8 wraps of 28ga Kanthal A1 around a 1/8" drill bit on an RBA and run it at 10-15 watts. That should put you at about 1.6 - 1.8 ohms with a decent heat capacity and heat flux. It's going to perform much better than a premade coil if the cotton wick is reasonable and not overdone.
On the other hand, if you buy coils in bulk on Ebay, they are a lot cheaper, if you want to stick to a premade coil.