I'll second Shedhorn in Ennis. That's a good one.
There's a gun shop in Montpelier, Idaho that is just unflippingbelievable, has the craziest collection of trophy mule deer I have ever seen, which makes sense as that country is amazing for producing them. But the guns were pretty darn impressive too. I would stop there every spring road-trip and they always had something for me I didn't know I wanted. It's been a while, but if anyone has been there recently, I'd like to know they're still around.
