I love this thermometer, it cost a fair bit but it's been worth it in my opinion. It seems to be fairly accurate, or at least consistent with others (on comparision with others when we can get them to work).
She won't take a dummy so those were out, and normal thermometers won't stay in her mouth through the wriggles. However with the in-ear one, it's easy to take a temperature even through screaming, tossing and wriggling.
Changing the covers is also easy, and they're available most places. Its possible to get them cheaper on the web, than in most chemists however (and this is the only downside) if you had a baby whose temperature needed taking often, it could get pricey.