There is a red parcel hidden in every level. When you find a red parcel take it to the grey and red postbox hidden nearby (some postboxes must be assembled first). Drop the parcel in the postbox and when you return to Barnett College enter the middle door on the right side of hall to enter the mail room. You will now be able to purchase the extra bonus that was unlocked by that parcel.
The following trick will give you 1 million studs in the unlockable Warehouse level in less than 3 minutes. When you enter the Warehouse level play as a bazooka trooper and go all the way to the far right-hand side of the level. There you will see a large target which you keep blasting until you can get 1 million studs.
You know the Barnett College has a place where you can customize your own character, right? OK, so create a character with a RPG launcher, and choose any lvl (Try to find a lvl that is filled with steel objects)When you get to the area where you want to destroy, open fire on all steel objects, and watch the fireworks.
Become the richest person ever.......and I mean EVER!!!!Added 7 Sep 2008, ID #861
Ok, all you have to do is enter in all the stud multiplier cheats (treasure multiplier cheats) and a siver piece will be worth 100,000 studs (treasure) and I bet you can't imagine how much a blue coin is.
Enter the following codes on the blackboard in the Math classroom (behind the 2nd door on the left in the main hallway) at Barnet College to be able to unlock the corresponding option at the 'Extras' menu where you then have to buy it. Cheats that are unlocked like this can be disabled from the 'Pause' menu.