Originally Posted by Hammbone
The choice is not one or the other.
I would say don't start an aquarium until you can somehow provide both LR and RO water.
Jim
the above quote hits the nail squarely on the head. this is not an "either/or" type hobby.
I personally have never seen RO water for sale at any Wal-Mart I've been to. I HAVE bought from Wal-Mart jugs of drinking water for $.65 per gallon. however if you test this water, I believe you'll find that the phosphates in it are astronomically high. this would defeat the whole purpose of buying water as the water I bought from Wal-Mart had higher phosphate levels than my tapwater.
and if that is the case, the RO unit is the better purchase (if you MUST choose). because if you have high phosphates, you are likely going to have an uncontrollable nuisance algae probably, which will cover all the nice live rock that you bought instead of the RO unit.
I bought the $100 RO unit from the auction site 2 years ago and it works like a charm. you can also buy baserock from Hi Rocks for $1/pound shipped. then get about 20 or 30 pounds of live rock. this should come up to $300-$400 total for all items. honestly, if you can't afford that, you may have picked the wrong hobby.