Every single part of this hobby costs money, and in my opinion, it's a lot of money. Even a simple test kit is 20 bucks!! You can go cheaper, but questionable test results is like driving without insusrance. It's a gamble, but you hafta be ready to make quick adjustments if necessary. Sometimes that costs money. If you go to the LFS and buy your water each week for $.50 a gallon. You buy, what, like 10 gallons?? That's 5 dollars a week? After a year that's $260!! You could buy 2 RO units at that price. But even if you can't afford the price of an ro all at once, you still hafta buy the salt. You have bought 520 gallons over the course of one year. That is at best 3 buckets of salt at what 60 bucks apiece? So now you've spent $420 on water alone!! But besides just the water and salt, you hafta purchase
test kits,
heaters (including one for QT and one for newly mixed water),
powerheads (" " " "),
filtration,
food,
QT tank,
the actual fish,
the clean up crew,
live rock, or even those bio balls
thermometer,
refractometer or even a hydrometer
those 5 gallon buckets,
a mixing bin (usually rubbermaid),
a substrate,
the actual tank and stand,
and a skimmer...
My point was not, if you can't afford an RO you shouldn't get into the hobby. My point was that an RO or skimmer are just a few of the many expenses in this hobby and if you don't have the funds then you shouldn't get the tank.
I have seen way to many tanks that are in extremely poor condition, and it all stems from funds. The fish are suffering, the hitch-hikers are dying the algae is everywhere, and their excuse is usually..."I know, I know, but I just can't afford it right now".
There are very few people that can maintain a "healthy" system with very little funds. It can definately be done, but you'd be hard pressed to find somebody that can DIY when they are new to the hobby.