Its actually pretty easy to set up a GFO reactor. I have the single reactor from BRS, and essentially all that goes in the sump is a small pump (I use the MJ1200, suction cupped to the side of my sump). There are then hoses coming off the pump to the reactor, which I have hanging on the opposite side of my stand. Another piece of tubing dumps water back into the sump. The reactor came with everything I needed to set it up.
Also, I didn't find I needed a reactor until I'd had my tank up for almost a year, and I only added one because I increased feeding to keep anthias and have been adding more sps to my tank. I've never really had a problem with algae growth. You can keep algae growth under control by using a good rodi, trying really hard not to buy frags that have algae on them, having a good protein skimmer, having an adequate clean up crew, doing regular water changes, and not overfeeding. If I were you, I'd try it without a reactor first and see how things go. Spend the money for a reactor on a good rodi and protein skimmer first!