Whilst certainly agreeing that probes should have a much longer life than you have experienced I would make the following note, which could be useful to some readers.
TESTING TEMPERATURE PROBES, quick, easy, and used in the industry:
Professional probes should be always be calibrated and recorded against 'test caps' to ensure the unit is reading the correct temp (both -18c and +2c are common combined tests in the UK). Whilst this isn't neccesary for home use, you can and SHOULD do another industry test; this is known as the 'Iced and Boiling Water Test'. This is based on the fact that even if the base unit is fine (proved by using test caps), the wire and probe may have become damaged. Industry practice tests this quite simply and you can too...
Boil a kettle, enter the probe, and read the result - this should be within 2 degrees of +100C. Similarly for testing chilled goods, take a container and fill with ice, then water, wait a while, and then probe which should return a result within 2 degrees of 0 degrees C.
If you want to know your probe is working OK then the water tests are a relatively reliable way to ensure that the entire unit is working properly - if you're only worried about hot food then how easy is it to boil your kettle and read off the result - giving you peace of mind that your equipment shouldn't cause you harm if you're trusting it for food safety.
Hope this helps anyone that is wondering if their kit is really doing its job correctly!