This makes absolutley s&%tloads of biscuits and is really easy and cheap.

1 tub margarine
1 can condensed milk
3/4c sugar
4c SR flour (maybe a bit more depending on stickiness of dough)

Mix all together and add whatever you like eg choc chips,cocoa,cornflakes,coconut,raw peanuts etc the list is endless.
Roll into balls,flatten and bake.

I roll the mixed dough into tubes and wrap in gladwrap and freeze them. I have defrosted and baked and also baked from frozen so it works both ways just as well.

Oh they need 10-15mins in about 180 oven.