Well, I have the gear listed in my sig, but it's far from complete (someday, a LD MK II). However, I do at least have a hard-to-find-in-retail beyer.
Oh, and if you ever want to demo Grado (I believe up to the SR-125), go to custom electronics near 72nd and pacific. It's right next to a pizza chain.
If you want to demo a DT 770/80 and a K240 Studio, you can always go to Guitar Center in Lincoln.
Otherwise, from the group that I know that lives here there is a K501, HD 280, ES7 (lincoln), and an HD 650 (my brother owns a pair; he lives in Lincoln, but works in Omaha).
As far as amps go, everyone I know is lacking. As to other Omaha goers, Gritzcolin is the only other one that springs to mind. I don't know what he currently owns.
That's about all I can help you with. There is always the trip down to Lawrance, KS for a meet (generally a good selection of cans for a fairly small meet). Great bunch of guys, too. Generally a meet happens about every 6-8 months.
Otherwise, PM me.
Nylan