Just checking - is there anyway of giving two postage options?

[natsmummum]

I have a small box to send (once sold) and it will be cheapest to send by AP to buyers on the Eastern seaboard. For potential buyers in WA, it will be cheaper to freight.

How do I offer both options?

Do I use calculate postage and qualify in the details of the sale that I will arrange courier to WA (as it is cheaper)?

And, if I do end up with a WA buyer, do I then adjust the postage manually on the invoice?

Any suggestions?