DIY still might be a good option, even though you're not too keen on it. With minimal cost & some PVC pipe you can construct something that's relatively quiet. Here's a YouTube link to one variation of a PVC overflow. It's a bit longer at 20 or so minutes, but shows sufficient detail to provide a good understanding of how it's done. I've seen others with various mods to the intake etc. but this one's a good start.
http://www.youtube.com/watch?v=65yVr7DiDls