Looking for suggestions to acquire digital signature certificates

Please see:
http://en.wikipedia.org/wiki/Certificate_authority#Providers[^].

Please read the whole article to get more understanding of the technology, purpose and available options. As one option, consider making a self-signed certificate, which you can create, say, using OpenSSL:
http://en.wikipedia.org/wiki/OpenSSL[^],
http://www.openssl.org/[^]
for Windows: http://code.google.com/p/openssl-for-windows/[^].

If you consider self-signing, do it and try it first, especially see how it looks in the browser (I know that you are not providing a Web application, but how will you deliver it? I assume, through the Web, otherwise getting a certification would be not so important). Before making a solution, learn all pro and contra.

See also, to understand the technology and benefits:
http://en.wikipedia.org/wiki/Public_key_certificate[^],
http://en.wikipedia.org/wiki/Public-key_cryptography[^],
http://en.wikipedia.org/wiki/Cryptographic_strength[^],
http://en.wikipedia.org/wiki/One-way_function[^].

—SA