"Compatibility"? The colours didn't match the ambient decor? Or was it just the "preferences" of someone with influence on the staff?
"Cost"? Yes; why not? It's as good a marker as any. Just as long as it's a calculation of "total lifetime cost", including consumables and (dare I mention it) maintenance.
Meanwhile, from what I've seen many (or even most) Patient Monitors are made by the same OEM, anyway. That is, there's very little to choose between them.
These things (that is, the selection of which new equipment to go for) are often dealt with more simply in the so-called "developing" nations. I'll leave it to you to read between the lines on that one.
Anyway, my advice to biomeds has always been to leave it to the staff to choose their own equipment. In other words, try to keep out of it. Otherwise you'll only end up getting the blame when the novelty wears off a little later down the line (and they'll ignore your comments about maintenance and training, anyway). In my experience, we never even got a nice lunch (or even a new Biro) from the sales rep!