So I bought 2 Thermaltake Smart Case II 120mm fans and installed them in my case back in April 2014 (a bit more than 1.5 years ago).
You can read more about them here: http://support.thermaltakeusa.com/Product.aspx?C=1438&ID=1726

I run my PC an average of 12 hours per day (so it's not on 24/7).

Recently the controllers for both fans failed and the fans started randomly changing speeds (anywhere from 1450rpm all the way to 2600rpm).
I had to use the sensor (comes with the package) to make the fans run constantly at 1450rpm.
If I disconnect the controller or use the jumper that comes with the fans they run at full speed (2600rpm), become very noisy and wouldn't last very long I suspect.
So using the sensor was the only way for me to be able to run the fans quietly.

My questions:
- Do you think the sensor will last several years (unlike the controller) ?
- If the answer to the question above is no, what brand of fans do you recommend (I need 2 x 120mm fans) ?

I noticed PCandParts only sells the NZXT brand. I read on Amazon a comment saying that one guy bought a NZXT fan and, a few months later, it started giving out a weird burning smell.

Keep in mind I don't want to pay more than around 15USD per fan and I do not need to have control over the speed (fixed speed fans are fine as long as they produce enough airflow to keep my case cool).
Apparently, according to the link I pasted above the Thermaltake Smart Case 2 fans produce around 35.5 CFM at the minimum speed of 1450rpm and it's enough to keep the case temperature within acceptable parameters.
Pcandparts has cougar and coolermaster fans.
It's at the bottom in the fans section where you saw the NZXT brand
DG wroteSo I bought 2 Thermaltake Smart Case II 120mm fans and installed them in my case back in April 2014 (a bit more than 1.5 years ago).
You can read more about them here: http://support.thermaltakeusa.com/Product.aspx?C=1438&ID=1726

I run my PC an average of 12 hours per day (so it's not on 24/7).

Recently the controllers for both fans failed and the fans started randomly changing speeds (anywhere from 1450rpm all the way to 2600rpm).
I had to use the sensor (comes with the package) to make the fans run constantly at 1450rpm.
If I disconnect the controller or use the jumper that comes with the fans they run at full speed (2600rpm), become very noisy and wouldn't last very long I suspect.
So using the sensor was the only way for me to be able to run the fans quietly.

My questions:
- Do you think the sensor will last several years (unlike the controller) ?
- If the answer to the question above is no, what brand of fans do you recommend (I need 2 x 120mm fans) ?

I noticed PCandParts only sells the NZXT brand. I read on Amazon a comment saying that one guy bought a NZXT fan and, a few months later, it started giving out a weird burning smell.

Keep in mind I don't want to pay more than around 15USD per fan and I do not need to have control over the speed (fixed speed fans are fine as long as they produce enough airflow to keep my case cool).
Apparently, according to the link I pasted above the Thermaltake Smart Case 2 fans produce around 35.5 CFM at the minimum speed of 1450rpm and it's enough to keep the case temperature within acceptable parameters.
NZXT is really good, you shouldn't judge them based on one review, things like that happen to even Delta Electronics.