I had a 20g reef tank and it wasn't too expensive to set up. You need a lot less live rock (which you can find on here for around $5lb), weekly water changes are only a couple of gallons so a pail of salt lasts forever, you can only keep a couple of small fish which are usually cheaper, you are limited to how many corals will fit (buy frags from here), etc. So yes, it's cheaper in these aspects but depending what you get, equipment can still be just as expensive. Some of the all in ones are nice and can be found used for good prices sometimes or you can just piece your own together. I have moved up to a 52g tank with a sump but I still miss my nano as you could get right in close and see every detail were as I find large tanks you look at the overall effect. So buy everything used and give it a try, I don't think you'll be dissappointed!
