Jamester,

Those speakers look very nice!

Now after seeing your setup I think I would definitely go with building a single mini monitor for the center channel. The only thing I think you would need to do is to make sure that you brought the center speaker forward a bit into the room. This is a rear ported speaker so it won't like sitting up against the wall.

As far as this speaker being expensive, this is still a DIY project and it uses the same drivers you have in your original project. The crossover is not very complex so all in all I think this would be a very affordable solution that will voice very well with your mains.