Welcome sleepy! It's generally preferable to get a center from the same maker and series as your mains so your entire front stage maintains a consistent timbre. If you don't mind not having a grille, I'd say
place a bid on this. Or you can get one
new in box for $256 if you prefer. If that is out of your budget, you should
contact Dennis Murphy at Philharmonic Audio and buy an Affordable Accuracy center channel from him. For $100 + shipping, you won't find a better center channel. It's a Pioneer SP-C22 center channel modded by a crossover god with an upgraded tweeter and impedance-matched crossover. It's got neutral tuning, and will probably blend reasonably well with your Monitor Audio Bronze mains.
For surrounds, again I recommend
Affordable Accuracy. Same reasons as the AA center.
Have you gotten a subwoofer yet?
The Monoprice 9723 measures impressively for the price.
See this writeup for details. If you have a larger room to fill (over 2500 cu. ft. or so), you could step up to the
Dayton SUB-1500 for a few dB more output. If ground-pounding and frightening small children is what you crave, save up about $600 - $1000 and we'll help you find something a little more grown up.