Bonus Tip: Whenever I am at checkout on any Site, where I have ordered something and I see that there is a box for insertion of a coupon code, I open another window and do a Google search for that site's coupon codes.
For example, if Seidio had on their checkout page a box titled "Coupon Code" I open a separate window and search for <Seidio Coupon Code> to see if somewhere on the Net a code is published. If there is one, I copy it and paste into the box to see if it works.
I have done that for many years and saved hundreds of dollars in discounts.
Bonus Tip: It helps to put in the exact term that the Site uses for entry of a discount code. I do this the first time around so to see if I get a hit. For example, if Seidio called their discount code "Promotional Discount Coupon" when in Google I enter that exact term, in quotes, to see if that term comes up.
This is important because if the Site you are shopping on does not use the word "coupon" for example, then you may not find any codes on the Net.
Anyway, using this often times results in 5 to 40 percent off on your shopping.
Bonus Tip: Also, companies use promotion codes all the time, many expire over time, some do not. Many times I have to try four to ten different codes before finding one that goes through.
Sidenote: there is nothing more satisfying than saving $50 or so at checkout using a code most do not know about or that the company has pulled off the site, but it still works.
Also, here is a Site that I found recently and it appears to be getting bigger as time goes on. Some codes have worked that I got from there.
LINK Coupon codes for thousands of online stores - RetailMeNot.com