Jaybird on HBT often sells his homemade FB's. I bought a full sized one that I use on my MT keggle and it works very well.
The Midwest cheap version has a 3/8" tube which might be restrictive if you are going to use March pumps. Having a full 15" hinged FB with 1/2" dip tube will increase flow/performance.
If you are a DIY'er and want to save $$$ you can modify this Amazon.com: Oxo Good Grips Splatter Screen with Folding Handle: Home & Garden
I did one and used it several times and it works pretty well, I just decided I wanted one that was more robust.