Why doesn't Plankton just hire someone to buy a Krabby Patty for him?

I'm sure others have thought of this, but it seems like Plankton could easily be able to obtain the Krabby Patty formula if he hired a random Bikini Bottomite to buy a Krabby Patty for him. Krabs would have no way of knowing this person was working with Plankton, so they could easily just order a Krabby Patty to go and then give it to Plankton, who could then analyze it and obtain the formula. Why doesn't Plankton try this?