You just about have to use brickseek.com. Spy a rifle out at a store and watch it on brickseek.
As to clerks who refuse to look and verify stock, get the store manager down there. People are people and some of them want the rifle themselves, some are just lazy and some are truly underwater with work and there are rules supposedly about 24 hour wait for an employee. I never have worked in a retail environment (since college) so I have no idea how it works. But if they will not go look, I bet the store manager can get them moving. The Walmarts I have dealt with on this Search for the Jabberwocky have been decent and helpful. But you have to do your homework.
There is another 7mm RM I am watching, the clerk tipped me he thinks it will go on clearance so I am watching on brickseek, it is still $389 as of a few minutes ago, who knows how this crazy thing works. And the one I bought this morning, it indeed shows it now gone at a selling price of $99. Yes, it can be a PITA, if you want a $99 rifle or a half price rifle then you gonna have to do some leg work.
Edit to add, the reason I am hunting for another is for my boss who does hunter education and they would raffle the rifle to make some money for their instruction. Not just to be greedy on my part.