They have plenty of them on ebay. Can get them real cheap from china if not in a hurry. A lot of them only read Celsius so make sure it will read Fahrenheit also. I like the kind with a 2 or 3 foot probe on them.
LOL 105 should spit them out real early.
You don't say what temp and humidity you are running at. It should be 99.5 degrees and 45-50% humidity first 14 days then 60 -70% during lock down. Some will disagree but that what I try to keep mine at.
If you have chicks hatching at 14 days then your temp is way to high, you need to get...