a metered postcard is a postcard that already has the stamp made into the the postcard. there is no need to put an adhesive stamp on it.
It depends on where you are sending it from.
99c
1 cent
32.00
35.00
As of May 2011 any postcard over 4.25"x6" and less than 6.13 x 11.5" is considered regular First Class and is $0.44
Yes, you can use a Forever stamp on a postcard, but it's overpaying for postage.
A postcard is $.28.
Get a first class stamp
The sell for 28 cents - for domestic use in the US.
Currently 28 cents for mailing within the US.