If you cant afford that much try ebay. I saw a portable 100gpd for $66 earlier today. It may not be as good as the ones from BRS but mine worked just fine for nearly a year before I had to change filters ($57). I have over 400 gallons in aquariums (ranging from 1.5 to 90 gallons) and do regular water changes on them. so I cant complain. I did add a BRS dual TDS meter to it when I bought it. That would hold you until you could get a better system.