While it is possible to get live edge slabs on Amazon (see here for details), it is not recommended as it is going to be one of the more expensive options (though in a pinch, maybe necessary).
This won’t be as much of a list with links like you and I wish it could be, but a VERY abridged version of this post.
First, check locally
The easiest way to do this will be with Facebook (the marketplace) and with Craigslist. Usually you can find someone within a decent driving distance that can offer live edge slabs. Occasionally you will find a local store/supplier near you that offers this.
Second, Ebay and Etsy
There are other artistic stores, however I have had decent luck getting pieces from these two. Etsy will usually run a little more expensive, but Ebay has a ton of selection for pretty decent prices.
Last, home improvement stores
The final place to check is going to be local or chain home improvement stores – they will often have a mild selection of overpriced live0edge wood. This is what to do if you’re in a bind and need something quick.
If all else fails, at least we have the monopoly that is Amazon taking over everything, even custom live edge wood slabs.