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Fiddler's Green in Austin if you want to go a little further south than DFW. Mass Street music in Lawrence Ks or Bradford and Franzke in KCMO.

This is way farther than you'd want to drive, but I think you'll like knowing about Big Muddy Mandolin in Missouri (formerly Mid-Missouri Mandolin). You can get a solid wood instrument for well under...

Hey man, might see if they have a Firey Music Company or Firey Brothers Music there in OKC. I'm in Tulsa, I havent been in a long time myself but they used to have a decent sized selction of mandos...

Byron always has a handful of decent mandolins. Honest Ron's will have some Webers. Lone Wolf Guitars usually has a few.

I'm not aware of a music store here in Wichita that carries a wide selection of mandolins.

Closer to you, Oklahoma Vintage Guitars in El Reno looks like they have a good selection.

The Walnut...

I can't really help you with OKC, but can say that a couple of hour drive isn't really a big issue prior to making even a few hundred dollar investment.
I recently went out on a limb and purchased...