Data Comparison Single Table Question - Mailing list pgsql-sql

I can handle this outside sql, but it seems like I should be able to do this in sql as well. 

1 table: countries. 
3 columns: id, name, price

What I'm trying to get is a result of the price differences between every country.

So if the data looks like (ignoring the id field)

Taiwain 30
UK 50
US 40

I'm trying to build a matrix that looks like:    Taiwan    UK    US
Taiwan    0        -20    -10
UK        20        0    10
US        10        -10    0

Any pointers would be appreciated.

Bryan