You might want to contact x2000 - he made a really nice McD restaurant, or Richabri - he made a really nice Retro diner. One of them might be in the process of making something like that, or, given their previous works, might be able to put something together like that relatively quickly. Steve Shanks - Poserworld - is another good possibility for this. He has several large buildings and exteriors. (Not to put down odeathoflife's offer, of course! I just figured that one of the three above might already have something similar if you're under a time constraint.) Depending on what it looks like, and price, I might be interested in picking up a Walmarty building as well.