I use just one Behringer B2031a (the 8" studio monitor) for this and it is great!

I also have the JBL LSR305s and I only use them for mixing, the 305s are a bit lacking in bass, but the behringer has just been better suited for the task of running the 11r in the room, sounds great at low volumes. In addition I have an Akai RPM800 that sounds good for this as well but it is physically larger so I use the behringer.

You should be able to find an 8" monitor on 'Bay for ~$100-$150.
I wouldn't recommend a 5" speaker for this as you will miss out on the real meat of the tone..