Ok, generally, the cheapest SSL I have found was a rapidSSL and it was $35 a year, I cannot remember where it was from. I can sell them for $60 AUD a Year which works out to be about $37.76 US a year.
With SSL, you need 3 main things,
1 Dedicated IP Address
2 SSL Certificate signed by a Certificate Authority Company (I.E. RapidSSL is a signed certificate)
3 ModSSL OR OpenSSL installed on your web server if Apache.
If you are unsure how to install an SSL certificate, I would highly suggest consulting who you purchased the certificate from, or the faster and easier method, do a Google Search, you always get something that will help you.