DIY isn't too terribly hard.
funny is was just telling
@Bret about this.
I built one out of glass in the past.
Just make a glass box with a gap on one side ( they dont seem to like going in a box with no flow)
I filled the gap with eggcrate, or just use screen or make it small enough nothing can get through.
( if you use plastic you can just drill holes)
Then leave the other side completely open and make a sliding door that can manually release when needed.
Feed inside the box for a few days, and then catch the bastard and feed em to the cat.
hehe