I've used different brand of mice/keyboards and I honestly don't really feel a difference in the long run because you can tune sensitivities and such. The only real differences in some things might be the way a mouse's texture or weight feels, or whatever a keyboard is made out of or how responsive it is. Unless you end up on the extremes of the spectrum (like say a keyboard is terribly unresponsive) you adapt that you won't notice a difference between most products.
I personally just stick with a logitech mouse and keyboard. After a year or two of using them I just got used to them and bought a couple of replacements just in case, and have been using the same keyboard/mouse models for like 8 years.
Edit: Also I will never buy a headset that is more than $40, they break no matter what the cost after some time and if you take a few steps to extend their life than you feel less of a loss paying $40 or less than if you had spent like $130+ on some headsets.
Also I'm not a huge fan of the expensive mice just having these odd shapes, or huge mice wheels, what happened to making a mouse that conforms to a comfortable hand shape?