TrackIR clips - get the DelanClip, hands DOWN.
Headsets - there are other threads here recently about this topic. I went through dozens in a collecting period of a couple years. Sennheisers (Game One, Game Zero, or the newer gaming headsets, the various GSP ones are great, but I've only briefly tried those ones in the shop, while I used the Ones/Zeros for years). Beyers are great too.
Probably the best combo for the money IMO is get the Sony MDRs, they are only $120, and add a mod-mic, or a high quality desktop mic from Blue or whatever. Running a DAC/AMP is great for this setup too, for about $350 you can get a decent DAC, MDRs, and the Mod Mic, and have a great audio setup, second to none IMO.
Also, if you just want a simple solution, the Astro headsets are great, I'm running 2 sets on 2 of our desktop setups, and am very, very impressed and happy with them. Solid tank like construction, lots of metal in them, great sound, etc.
Just understand there is more to it than just the headset, a good DAC, or even a sound card, will make an astonishing difference over mother board sound, even the very best MB (I use Asus $400 mother boards with "wizzy" sound, and it sucks compared to even a $100 sound card) can't compete with a sound card, or better yet a good DAC/AMP.