If you are scrounging and building to save money, go for the TheMightyHobie18 mast and upgrade to a carbon mast later on as an option.
If you want to purchase used sails later on, you should aim for a APHC wingmast.
If you are going to build your own sails as well and are extremely into saving money, go for the TheMightyHobie18 mast or any rotating beachcat mast you can scrounge. Should still be some alu Tornado masts lying around after the switch to carbon masts in the T-class (I have two in my garden and one at the club).

Depends on your wants and needs