Mollie79 - as far as cost of a
SW setup - this greatly depends on wether you want a fish only, a fish only with
live rock (
FOWLR), a reef tank,
live sand - and this is also dependent of course on the size of tank you want as well. A tank such as a reef tank for corals, etc., requires substantially more gear if you are going to do it right. I might suggest that if you want to look into tanks, start out small, there are setups such as nano cubes in the 25-30gallon range, approx, 110-130L for you folks aross the pond, maybe get an idea if you like it. My best advice is decide before hand what you want to setup and then visit as many web sites (and research books) as possible and read/research. There are basics that everyone agrees upon, but when you get into gear; type/cost, mfgr., and configuration there are many different opinions. Also add in the cost of supplies for water changes, salt mix (mixing containers, heater), chemicals/additives, do you want
RO water - most go this way, especially if you want a reef tank, testing supplies, filtering, live rock?, live sand (read about curing if you use these)
But again, research, research, research, then layout what you want and what you will need. It is best IMHO to identify exactly what you want and buy the best you can afford, but don't settle for mediocre gear - your livestock will thank you and it will make your life easier.