I would look more into what you want in an RDA, then browse online retailers. Some good features are single/dual coil airflow and a positive block for separate coils. Some RDAs also do airflow differently, either just a cap, a cap with airflow control on the inside, or a cap with airflow control on the outside.
The freakshow is a nice little choice and the bottom airflow is nice. Although it doesn't have a center block it is still easy to use. I have the mini and I like the small chamber a lot, but some people complain about leaking due to bottom airflow and wicking issues.
As for an RTA I would look into the aromamizer RDTA, builds like a RDA. The mutation x mt tank is looking pretty nice and easy too.
If you need help finding deals online we can supply that too. I've seen many RDAs go for under $15, granted it's not the newest stuff.