The Office Max lights are made by a company called Tensor. Both my roommates and my gf work from Omax, I got them at the great price of free for my Mini-S. They are good but you'll have to put something under them to raise them high enough for the M. That's what dissuaded me from using them on mine tbh.
Also, if you're going that route, having them staggered on the sides looks great and distributes the light better. I don't know what kind of space constraints we're talking about here, but the lights only go out about 4" max from the sides, and you can use some of the corner moulding for doorways to raise it (the square ones with all the circles, I don't know what they are called exactly), and they are generally the same size as the bases of the ott-lites.