we have had a few sets at work due to epilepsy.
the one I liked the most was this one for $299, I liked that I could see what she is doing even in the dark due to infrared night camera function
Oricom 700 video one
it is basically the video version of this one though which is still good (we have it at a differnet work house)
oricom 210
we have also had this one $129 did the job of hearing and being able to talk to them but did get a bit hit and miss if outside due to brick walls on house
Phillips DECT
the ones I hated the most were the Tommee Tipee brand ones, they were staticky and did not work through bricks.
[she often lays on her bed during the day so if we are outisde with someone else we clip the parent unit onto ourselves so can still hear/see seizures]