I need help to get the keys they open display cases with at Target and/or how to get a mold of that key.

Molotov it

They're store-specific. Standard round keys that are not supposed to be duplicated.

I think your only hope is to get a 7 or 8 pin circular lock pick. They'll run you around $80 but if you're good then you can make that money up in no time.

^ that got me thinking, i wonder if anyone has ever picked a lock to a lockpick case

Hmmm. That's one of those things to ponder. Like, there are a lot of colored soaps out there but why is the lather always white?

I used to work at target, and those cases are alarmed. whether a staff member or you opens it the alarm goes off. and if it isn't the staff member who opened it then they will notice pretty quickly what you are doing.

The alarm isn't to loud but its annoying as fuck and any staff within 50 ft (there will be one) will notice.