A simple secure certificate should be fine if you intend to host just a form or two that asks for a user's credit card details.
Verisign are great, but if you're looking for a more affordable solution, you might find Thawte's services appealing. Thawte was acquired by Verisign last year, but still provide a more affordable 40-bit and 128-bit certificate. (I use Thawte's $125 SSL Certificate on the site's I design for clients, and have never experienced a problem with the product or Thawte's service).
Their products can be found here:
http://www.thawte.com/certs/server/contents.html
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