[DNSB]

Originally Posted by gbm

This one will work for you in Canada.

I'd suggest this one instead. The one you posted will show prices on Amazon.ca if the link is to amazon.ca. The version I prefer converts .com to .ca which gives me results from the vast majority of Amazon links.

This is the one from the link posted by PeterT.

// ==UserScript==
// @name        MobileRead Kindle Price Check (amazon.ca)
// @namespace   kakapo.public
// @description Checks price of Kindle ebook links in MobileRead forum posts. Translates amazon.com links into your local site, please install the correct version.
// @include     https://www.mobileread.com/forums/showthread.php*
// @version     3
// @grant       GM_xmlhttpRequest
// ==/UserScript==

var site_regex = /^(http|https):\/\/(www\.)?amazon\.(com|ca)(\/.*)/;
var migrate_regex = /amazon\.com/;
var migrate_replacement = 'amazon.ca';
var currency_prefix = 'CDN$ ';

var ebook_url_regexs = [
  /^\/dp\//,
  /^\/[^\/]+\/dp\//,
  /^\/gp\/product\//,
  /^\/exec\/obidos\/ASIN\//
];

var check_price = function(elements, url) {
  var xhr = GM_xmlhttpRequest({
    method: 'GET',
    url: url,
    onload: function(response) {
      var data = response.responseText;
      var pos0 = data.indexOf('class="priceLarge"');
      var pos1 = data.indexOf('>', pos0);
      var pos2 = data.indexOf('<', pos1);
      var price = data.substring(pos1 + 1, pos2).trim();
      if (price == '') {
        price = 'N/A';
      }
      var color = price == 'Free' || price == currency_prefix+'0.00' || price == currency_prefix+'0,00' || price == currency_prefix+'0' ? 'red' : 'blue';
      pos0 = data.indexOf('class="iou_cust"');
      if (pos0 >= 0) {
        price += ' already own';
      }
      for (var i = 0; i < elements.length; i++) {
	elements[i].insertAdjacentHTML('afterend', ' <span style="color:'+color+'">('+price+')</span>');
      }
    }
  });
}

var a = document.getElementsByTagName('a');
var to_check = {};
for (var i = 0; i < a.length; i++) {
  var url = a[i].href;
  var parts = site_regex.exec(url);
  if (parts) {
    if (migrate_regex) {
      url = url.replace(migrate_regex, migrate_replacement);
      a[i].href = url;
    } 
    for (var j = 0; j < ebook_url_regexs.length; j++)  {
      if (ebook_url_regexs[j].test(parts[parts.length-1])) {
        if (!to_check[url]) {
          to_check[url] = [];
        }
        to_check[url].push(a[i]);
      }
    }
  }
}

for (var k in to_check) {
  check_price(to_check[k], k);
}