I think you’ll have a hard time finding a site in English that carries any Karlsruhe merchandise. If you’re comfortable with German, you can visit the club’s online shop at http://ksc-onlineshop.de/ A jersey can run between $75-$95 (55-65 Euros) plus the shipping, usually another $30 or so to the US. The t-shirts are more in the range of $35 plus the shipping. The exchange rate is going to cost you, but there’s really not an alternative that I know of.