It would help to know how you are planning to power it. I use a Genz Benz Shuttle 3.0-8T as a monitor frequently and it works very well for that.
The Shuttle 3.0-10T is also good, not much bigger and has a tilt-back leg which can be good for a monitor.
You can also buy the cabs without the head.
There are no doubt cheaper alternatives but the Shuttles make very good monitors IMO.