The best thing to do is find a couple of reputable butchers close to you and go to see them. They'll be able to give you prices and will be able to show you the meat they can supply.
If they are unfamiliar with the US cut names (as they probably will be) then you may need to describe them. There are a number of threads on here discussing this so you should be able to find decent descriptions.
There'll be a bit of trial and error getting the exact cuts you want but don't get too obsessed with getting it exactly right. People sometimes get the idea you won't get good pulled pork unless its a Boston Butt for example, however if you go in and get a neck end from the butcher, you're getting most of the same muscles and you'll get a good result.
Ribs and brisket will always be the challenge, getting them meaty enough can be difficult.
If you want a good piece of meat for your party that doesn't get mentioned much on here, ask your butcher for a chuck roll, you cook this like a brisket but instead of slicing, you pull it like pork. It's a great thing to eat. Here's a guide from the virtual weber bullet that you might find helpful if you do a chuck.
http://www.virtualweberbullet.com/chuckroll.html
I think you may struggle to do a chuck roll on your kettle due to space limits.
