So you're planning to buy "Now That's What I Call Music, Vol. 43." Hey, I'm not here to judge.
(Don't worry if the voucher comes up showing Oakland County, which is where I live. All you need is an Amazon account that's been set up with a valid credit card, and the voucher should work.)
Just to clarify, that code you'll eventually get is good for $3 off any MP3 album priced $5.99 or higher. So, for example, "Now 43" sells for $8.99, meaning you'd get it for $5.99 after applying the voucher.
The process works like this: click through to AmazonLocal using the above link, then click Get Voucher. Complete the order, then click the link that takes you to the Your Vouchers page.
You'll see the $3-off voucher at the top of the list, most likely with a "processing" message alongside it. Click your browser's Refresh button a couple times, and soon enough you'll see a View Code button.
Next, clip Copy to copy that code to your clipboard, then click through to Amazon's MP3 promotion page. Click Enter Your Code, paste in the code (Ctrl-V, of course), and then click Apply.
Whew! You're finally done. I agree: that's a lot of hoops to jump through just to save three bucks. On the other hand, you just saved three bucks in exchange for a minute's worth of clicking. Not a bad return.
The voucher is available only through the end of the day today, and must be redeemed no later than September 2.