I like this style as well and I've been slowly collecting them from buying beer and reusing the bottles. I purged most of my empty bottles when I moved states three years ago but I kept these bottles. I think they look sleek and hold pressure better than a standard longneck. Funkwerks here in Colorado used to use them which helped fill in my collection but like most breweries they have switched to cans for their 12oz packaging which put an end to that.
If any local breweries use those bottles or used to use those bottles you might contact them and see if they would sell you a few cases. If they've switched to cans they might be thrilled to unload empty glassware to you.