Hi Chuck -
There's a lot to choose from out there, and it really depends on how much you want to spend ...
If you're up for building a shell or repurposing something, then you'd just need a set of controls: stick or yoke, throttle / collective, and pedals. There are two games in town for those at consumer-type prices:
If you are, as I suspect, really looking to buy a purpose-built cockpit or cockpit-type thing then you might look at:
If your budget permits, Fly-it makes very nice full cockpits, both helicopter and fix ed wing:
Precision Flight Controls offers a good mix of ala carte controls and cockpit shells:
Some others to look at:
Sim Aviatik makes some nice airliner and warbird (P-51 / Me-109) cockpits - unlike the rest, though, I don't have any hands-on experience with these:
If you really want to go all out with enclosed cab and full motion, there's Red Bird:
Though if you get one of those, I want to be one of the kids!
Hope this gives you a starting point - feel free to follow up with any other questions as you get closer. 11 years of my previous life were spent in the consumer flight sim business.