no, it could be very cheap and even bigger and even more efficient with extra bells and wistles if you made it yourself, its a very simple process, pick between a drilled tank and/or a siphon overflow, then build a wet/dry filter (many links) with your mechanical filtration of anything you want, then you can upgrade and add a refugium to the sump growing easy to grow plants like java moss or java fern to help reduce nitrates away from the main tank, then just buy a return pump and pump it all back to the tank, use maybe a 75-100 gallon sump, dont have to use glass, plastic would be great.
Not many people buy wet/dry sumps since they are so expensive and making it yourself saves you so much money.
Hello everyone! I am looking into getting a sump filter for a 300 gallon freshwater aquarium that will house various large cichlids (South American/Central American). What type of sump filter would you recommend? I want something with VERY high flow rates and A LOT of mechanical/biological filteration. So I'm assuming one that will be very large and costly. That is fine, just want to know what brand everyone recommends 
