I think I am genetically programmed never to go in to pet supply stores without buying something...
There are just too many tempting things in there to try and get your kitty to play / have yummy snacks / relax and be comfy. It's not fair, everything in the stores other than basic food, litter and health supplies should be behind screens and only staff be able to get them out on request. I avoid going in to pet stores at all costs but when I get caught out I always end up with a large bag full of 'stuff' for Mouse.
It's not like he doesn't have enough toys: he has at least 2 toy cuboards full and that's on top of the little pile that gets scattered around the floor every day.