I had a client who needed to use the Paymate Payment Gateway which is a popular Payment Gateway in New Zealand and Australia. Paymate is similar to Pay Pay Standard i.e uses http post.
Please see my blog below for some more indepth details above the provider or you can download it from here.
You will require Visual Studio in order to install.
http://skiltzonnet.blogspot.com/2008/09/paymate-payment-provider-for-dash.html
ASP.NET Freelancer. Visit my blog for contact details.
skiltzonnet.blogspot.com