So long as you are holding your discount card, and paying with cash/redcard that was in your posession when you entered the store, that $399.99 PS4 is yours for $359.99 plus taxes.
If you do something stupid like lend your discount card to a friend when you're not there, or go in together and hand over your discount card then the friend pays, or loudly talk about how you saved your friend 10% in front of AP/TLs, you're looking for trouble.
The discount card is meant to be for your use only, but if the transaction has no reason to look weird, it wouldn't be a problem.
A few weeks ago I bought a laptop, after price matching a website and TM discount and red card signup, I got it for way less than we were selling it. If I were buying that on a daily basis, I expect I'd be having a chat with AP/STL by now. As I only did it once, it looks like what it is - bought a laptop for the best price I could. There is, as with so much, a reasonableness threshold - if you've already bought 3 or 4 of them, this is not a good idea. If not, it's technically against policy but you'll be fine.