Tim,
I think the Capricorn aluminium mast is around $1300 AUD.
$1079 USD.

How much does a I 20 blank carbon mast weigh?

I think you should be able to extrude an aluminium wing mast 9.2m (approx 30ft)long for around 16 to 18kg.ie 36 to 40lbs.

Interested to find out how much weight they save by using carbon.

Regards,
Phill

I know that the voices in my head aint real,
but they have some pretty good ideas.
There is no such thing as a quick fix and I've never had free lunch!