The planet offers cheapest GeoTrust Quick SSL Certificate for only $49/year compare to $249 offer by official website.
You may order the cheapest Geotrust Quick SSL from here
There is another SSL at even lower price, RapidSSL for only $14.95/year . It is compatible with IE 5.01+, AOL 5+, Netscape 7.0+, and Opera 7.53+ .
You can get this cheapest SSL from here
If you happen to know where you can get even lower price SSL, please tell me via comment form below.