US Postal First Class Mail (with delivery confirmation) starts at $1.69 for up to 4oz packages.
Not that it matters that much, but that is incorrect. Besides, the OP stated :
$0.99 with free shipping from the US
Using the Post Office, the minimum charge is $2.07 for a package by First Class Mail (with delivery confirmation). eBay, and others, do offer discounts. Maybe you use one of these other service providers?
I use eBay fairly often, I think their price is about $1.80 or so, but it's been a few months since I shipped anything through them. Envelopes aren't free and I'd be surprised if the cable weighed under 4 oz.