I did a fair bit of research before purchasing the first Rythmik sub to "supplement" the bass for the Maggies. I originally bought a cheap Rogers sub from JB HiFi for a couple of hundred bucks to test my theory that adding a sub would address my desire for some more bass weight. (For my taste I found it very difficult to get serious bass weight from the Maggies without adding some low end grunt). But being a cheap sub it added the weight I was after but was very ill defined and sounded pretty average. However the test confirmed my proposed solution.
I started with Maggie 1.7's
I use a pair of Rythmik F12SE subs with my 20.7's (as do many other Maggie owners) and they integrate very well.
As previously suggested, 2nd hand might be the way to go to keep them within your budget.
I just did the firmware update to V4.8 and whilst it loaded successfully - I have a problem Houston!
They have made changes to USB connected drive mounting and sync and now I can't access my library.
Anyone else using MPD with a connected hard drive and having problems with the update?