Get GoDaddy .COM domain or renew them at discount price
https://addons.mozilla.org/en-us/fir...oupondetector/
https://addons.mozilla.org/en-us/fir...couponshelper/
https://addons.mozilla.org/en-us/fir...s-at-checkout/
https://addons.mozilla.org/en-us/fir...on/priceblink/
or simply visit http://addons.mozilla.org/ and enter word coupon or coupons into the search box and you will find many such plugins...