We had a bit of a play with the Vodafone numbers, and reckon it would work out roughly like this -
Plan $40 $60 $80 $130 $250
break fee 0-6 months $450 $480 $700 $880 $1,050
break fee 0-6 months + GST $506 $540 $788 $990 $1,181
16GB VF price $619 $569 $519 $319 $0
32GB VF price $799 $749 $699 $499 $179
cost 16 $1,125 $1,109 $1,307 $1,309 $1,181
cost 32 $1,305 $1,289 $1,487 $1,489 $1,360
If you cancel immediately after buying you probably get back a pro-rate amount of your first month's fee. Might be worth checking out, otherwise you have to add that onto the price as well. In that case obviously the $60 plan is the one to go for...
EDIT: Now with ETC GST goodness...