@lilblister can't have a bakery on a home lot as it's not a business/retail lot
you need to own the venue to place items in the displays and the lot type is set to hang out and yes other sims will help themselves to stuff ( especially once any lot is set to hang out ) but they do buy the baked goodies
I found if i'm on the bakery lot I own you/I do need to go to buy mode to place the goodies into the display case
if I bake at the home lot with the bakers oven then once the sims puts the plate down I can drag and drop to the personal inventory I then just move the camera to the bakery and can drag and drop from the personal inventory there are some thread going on about the bakery over at the sims 3 on how best to restock I have no idea which thread would be best to link here for you to look at but they are/should be easy enough to find
a link to a thread with tips
http://forum.thesims3.com/jforum/posts/list/748010.page