To unlock Secret levels 11-100 You have to Beat levels 1-10
When a character is deleted, all equipment on that character is unequipped and placed in storage in the Base Camp.
Process: Create mutliple extra characters(just do an auto create until it says you are full, which is at 20 total characters) then delete all the extra characters. All of thier gear is now in storage. Continue doing that until you get bored or feel you have enough. Remove all of the items from storage(dont worry about max weight, it doesn't apply aboveground) and sell them.
You can get the best store-bought equipment for all five characters within half and hour, depending on the classes made and your speed. Granted it isn't alot of money later on, but by then you wont be buying much, now will you?