The biocubes are nice... but word to the wise...
When (not if) you get addicted to SW, you will want to upgrade and it will cost you. It happens to all of us. Trust me, I am sure someone will chime in and say the same thing. Get the biggest tank you budget will allow, personally, I say get a nice shallow 55 gallon and you'll be very happy with it. The equipment is will priced, pretty common used and there are a lot of things available to you.
the other real big thing about Nanos is that they are finicky. They aren't as forgiving to someone starting out and it will be very frustrating to have a small mistake turn into a big one.
Also, everyone says "oh, I just want corals and some clowns." but when you start to see other really neat things, you'll want them and your tank will be too small, hence the upgrade.
Just some advice...
I would suggest the 29 gal biocube. They are all inclusive and they are pretty inexpensive if you pick them up used and they are easily set up. Alot of people have them here and like them.
Personally, I started with a 10 gal, that upgraded to a 25 gal. then I went to a 45 high, and then I bought a 200 gallon custom tank (used). That was a reef, then thought I would set up a 16 gal reef. then took it down and put up a 55 gallon reef and the 200 gallon is a swim tank. I am finally happy... and it just goes to show you.... get what you can afford, and get the biggest you can fit. (with in reason) lol
good luck with the hobby!!