I would try the Wal Mart on 535 just north of 192. Cheap gas in the area, not as touristy, and good prices. This is coming from a person who usually does not shop Wal Mart.
We went of a Tuesday around noon and it was the least amount of people I have even seen at a Wal Mart during the day.
I cannot recall if Orlando has any Sav-A-Lot stores, which are similar to Aldi.