U will neverbe able to pull of keeping an anemone in a 5 gallon. I have a 12 gallon and I'm about to dump it out and go bigger because the smaller the tank the harder it is to keep good water conditions and you need pristine water for an anemone. If you really want to do saltwater go get a 20 gallon but first spend about 4 days reading everything and expect to spend 300-500 dollars and not put fish in it for 2 months. I'll tell u from experience it's NOTHING like freshwater
I agree after carefully reading the NANO SW sticky on starting up a tank for the last month n a half, it will not be cheap, and a lot can go wrong if you do not exercise proper care and execution of building the tank and maintaining it.
From purchasing the powerheads, heater and filter
-to setting up the water with SW Salt
-to adding the liverock and organizing properly in the tank
-to letting it cycle and letting the liverock "grow" and build up bacteria and micro organisms
-to constantly topping the tank off with water and regularly checking salinity and other parameters you don't check in FW tanks
-to adding your first 'clean up crew' members
-and in the next 3 weeks or so, finally adding your first and usually only fish (sometimes 3-4 if you have a 20G)
It indeed seems very discouraging when you learn all you can about doing it, but it can also be really FUN and very interesting, considering all the things living in the tank besides fish.
JoeyB, I quoted you but this info is really meant for thanatos n co. Obviously you have the experience with SW