I recently had a problem with dust on my sensor. Bought an ear syringe blower (5 $) and tried to blow off dust in cleaning mode but it did not work. Then I used a fine synthetic brush I picked up in the arts (2 $) and did a gentle sweep over the sensor followed by blowing again. All the dust came out! This might be a cheaper option if you don't wanna buy those expensive cleaning kits.
many times before i've suffered the whole "you get what you paid for" incident.
i dont feel like trying it with my expensive camera.