My GF suffers from diabetes, and she uses same needles on her insulin pens for several days sometimes. And she pins herself everytime she has a meal..
She changes the needle only when she feels its starting to hurt more..
Never once had an infection, and she has had diabetes for 10 years now...
I'm not saying you should use the pin for weeks, but don't be afraid of using the same one several times. As long as its clead and you don't touch it with your dirty hands after taking a shit:naughty:.. just kidding, but keep it clean.
Almost forgot to mention, she does this even though she has free supply on pens and needles.
//M