I dont know a whole lot about the RO 110. Ive never had one of these but I can tell you this from what I do know. Most skimmers are over rated by the manufacturers. So if you are going to run a 75 gallon with a 30 gallon sump your total water volume will still be around 75 - 90 gallons roughly depending on water displacement by rock and sand and how full you'll actually run your sump. So you probably need to look at skimmers ranging in the "rated" 150 - 200 gallon range due also to the planned heavy bio-load.
The $200.00 price range will be tough so I might would try and find something used. I got a used DAS EX2 rated for 250 gallons for $100.00. All it really needed was a new o-ring for the cup. A call to DAS and one was in the mail for $5.00. If you can locate something like that then you can save up some money and get something a little more appropriate like a RO Diablo 200, Reef Dynamics INS 135 or 150, RLSS R6i etc etc etc. All of these are in the $350.00 - $400.00 range I believe.
