mutation x, even the authentic is cheap, but the clones are even dirtier cheap. quality no frills good performance atomizer, deep
juice well, tons of airflow options. Just make sure you get one for the type of mouthpiece you want to use on it, there are some wide bore topcap ones where you cant use a 510 driptip on it.
originvape.com has a few mutation x and mutation x styles with small driptips or the widebore driptips, to fliptop caps for 20-30$
eciggity.com has 2 510 driptip mutation x clones for 15-20$
its a real easy deck to build on, and the juicewell is real deep so u dont worry about leaks like some other RDA's.
if you decide to go with something else, just make sure you get an RDA with good airflow options. The mistake I made with my first one is that it didnt have any airflow options, just one tiny non-adjustable 1mm hole. I bought the IGO-L cuz I saw it was cheap, but i ended up throwing it in the trash as soon as i got my mutation x.
bad airflow = no vapor = no flavor = no cooling = scalding hot atomizer = waste of $$