I thought I would sart a thread here rather than in the intro section to answer your question.
RO stands for reverse osmosis with an RO unit setting you back about $300-400 in Oz.
What it does is denude water of any and all minirals leaving pure water. It does this by first filtering the water through micro filters and carbon filters and then sending the water past a semi permiable membrane from one side of the mebrane you get pure water from the other side you get more concentrate or waste water. The ratio of pure to waste water is about 1:5.
There are a number of sites that have info on RO just do a search.
Having said all that I am aware that somebody has bred zebs in Melbourne without using RO water. They use straight tap water treating it with prime.
Until I heard this and also reading through the various posts on this site, I was using RO water but have now changed over to using aged tap water. The advantage to me of using straight tap water is I can do more frequent water changes and achieve this with much less effort.
Since I changed over to straight water (PH 7.5) a view of my Zeb's have started sitting accros the entrance of caves, so as long as I have soem willing females the moment shouldn't be more than 3 months off.

I assume for the price you will be getting fairly small zebs so you will need to be growing them for a while. Mine have been growing for about 2 years having obtained them at about 3cm.
Cheers
Andreas