The sales-people or manufacturer representatives often does not understand this aspect.
Your best bet may be finding a 1080p60 capable display, and count on the bluray/xm/laptop to do the rate-conversion (repeating every frame exactly twice). Most connected PCs will be working at 60 fps, so a display that works well on PCs in general, might work well for 1080p30. Perhaps you should use this as a guide when reading reviews of displays, then test the candidate yourself with the equipment you will be using.
-h