Even the cheapest ProAim mattebox runs you well over $280 (including shipping), so this new single filter MatteBox complete with side flags for half price + free shipping is a much better option than the recent cheap plastic version (found here) that holds NO filters.
The shallow hood looks like it can accommodate wide lens setups, but no information on if the filter can be rotated (for polarizers or grads). Not the best of the best, but I know some of you were excited about the $70 dollar version matte boxes for pure aesthetics, so I suggest you at least hold out and get something like this. Not only uses more metal in construction (except hood), it looks much better, and also serves a better purpose by holding a filter (like ND). New mattebox can be found on eBay (click here).
[Update] Prices starting to move upwards since this post. [Update again] Seems like they dropped pricing back down hearing complaints.
Inexpensive Single Filter MatteBox with Full Flags