I purchased NEC MultiSync PA271W on sale for ~ 800.00 or so. It is very good and I can calibrate it, unlike my iMac, which is way too bright.
Cameras: 1DXII,5D III, 5D II. Lenses 24-70 2.8L II IS, 70-200 f4L IS, 70-200 f2.8L IS II, EF 400 5.6L, 300 2.8 IS II, Samyang 14 mm 2.8. Flashes: 600EX-RT X 2, ST-E3-RT, 580 EX II.
Plus lots of stuff that just didn't work for me