A family fav with us is ice cream cake - also not mega cheap but goes a long way and is always requested and demolished!

I use a 23cm spring form pan cover the base in foil then cling wrap.
Soften slightly ~ 2L of vanilla ice cream (I use medium priced brand so Peter's/Paul's etc)
Mix in 1 packet of crushed vanilla meringues and ~ 1 small packet of frozen raspberries. Try not to smoosh everything up too much. Put in tin, smooth top with back of a spoon and cover with foil. Refreeze. This generally covers our family of 18.

An alternative is to do mix chopped Mars bars/toblerone and omit the meringue. You could also mix in some fruit mince and top with some choc sauce (or Ice Magic) for an alternative Christmas Pudding. Heaps of scope to do whatever you like really!

Merry Christmas!