I re-sell for Comodo too and will beat both the Intel and Tucows deals for anyone here in addition to personally walking anyone through the certificate ordering and signing process on any platform. The verification process can be a little bit confusing but I'm available almost any time via phone and email to answer any questions (or PM me here).
Use the coupon code CPNINDIEGAME on my order page at http://codesigning.ksoftware.net for a 25% discount -- and that applies to all of the products, from 1 to 5 years. Use that discount on a 5 year cert and the per-year price is just under $55 per year, or essentially 2 free years. The single-year price drops to $71.25.
Just one technical clarification in your original post though -- you mentioned that when the certificate expires that the signatures expire and that's not strictly true. If you use a timestamp with Comodo certs then the signatures remain valid even after the certificate itself expires. My free code signing utility kSign does timestamping automatically if you're signing on Windows but I can walk anyone through doing it on other platforms as well.