Are you wanting an RTA or a tank with pre built coil heads?
For a cheap RTA, I really like my zephyrus V2. I got mine for 22 bucks. It also has pre built coils available, but I never got a good vape with them.
For non RTA's, I don't really have any good recommendations as I don't use them anymore. Many people seem to like the kanger subtank minis, and I believe they can be had for relatively cheap. I've heard mixed reviews for the cubis tank, which was released to go with the cuboid by joyetech. If you are interested in subohm tanks that have a good rba section, then I wouldn't recommend this one. The rba on the cubis is really wonky and hard to build on from the reviews I've seen.