Also another option.
Create HUD like layer called SHOP. The layer is hidden by default.
When the player opens the shop.
Set timescale to 0 to pause the game.
Show layer "SHOP"
on close of shop
hide layer "SHOP"
timescale 1
There might be some trouble with it, but it saves effort in regards to enemy positions and states.... if you go with the prior poster. There is a plugin called Spritebank. Which I think will do what you want.