[ATDrake]

^
No, Kindle users can take advantage of Kobo coupons (I used to do it for years before I got my Sony). But you'll have to be willing to strip the DRM (unless your chosen book is already DRM-free) and convert in order to read on a Kindle (though I notice you have a Kindle Fire, so maybe you'll be able to install an ADE-DRM-compatible ePub reading app?).

Anyway, Kobo coupons can be used on almost any eligible title in the Kobobooks.com store (allowing for a compatible store country, that is, as some coupons will only work in certain countries). You can see couponable titles in the search results by clicking "Items eligible for promo codes" in the sidebar, though sometimes this is glitchy and the filter lets through items it turns out you actually can't discount when you try, or perhaps it needs a code tied to a special promotion. Also, some coupons can only be used on a selected list of books, while others are more general use. Many codes are single-use only, but some can be used multiple times.

To use the codes, make sure to set up your Kobo account so that it uses the shopping cart instead of 1-click buying (this is a setting in your preferences). And to actually use them, it's as simple as "Add to Cart", going to the checkout, and near the bottom of the checkout you'll see a box in which to enter the promo code, which will give you an error message if your code is not applicable, or a warning if the book is not couponable at all.

A caveat: sometimes books are only available in the kepub format, or sometimes some sort of other Kobo-device-only format for certain academic titles. You may or may not be able to get one of the kepub-DRM-removing tools to work for you (I haven't managed it yet). Anyway, to check what format the book actually comes in, you'll have to "Save Preview" for the title, and then go to your account library to have a look under the listing to see what if any formats it's downloadable in. If it doesn't say either "ePub (DRM-free)" or "Adobe DRM ePub" next to the Download Options line, then you may wish to rethink your prospective purchase.

The dedicated Kobo coupons thread will have much more info and tips on making best use of the coupons, but these are the basics.

Hope this helps.