Unfortunately, there are no pre-made "sump kits" for lack of a better term. This part of anyone's system is very personalized. You pick:
- the size you want the sump to be
- how you want the sump set up
- how you want the water routed in and out of your sump
- how much flow you want, which encorporates the return pump and such
The list can go on and on. If you want to avoid this whole aspect of a salt water setup, then a hang on the back skimmer will be the easiest way out. They also make hang on refugiums. Once you get over say...75 gallon tanks though, this hang on equipment becomes relatively unaffective.