The Dayton DVC is still $99 with free shipping right? I'd probably go with that.
Edit: Actually just modeled the Mach5 MJ-18 and it looks alright. You can get it for $106 shipped from soundsolutions.
http://www.soundsolutionsaudio.com/s...d&productId=52
In 9-10ft^3, tuned 18-20Hz, with an 8" port. You'd have zero port noise, ever.