Will most probably seem like a dumb question, but it won't leave me alone.
I got my T prescription yesterday (12/11/12), as well as oodles of needles - namely the ones that came with the syringes (25g 5/8"), and 18g 1.5" for drawing (I need to stop by the drug store on Friday for the 23g 1.5" needles, alcohol wipes, and a sharps container before I give myself my shot).
I was looking at
imed.com, and found that they sell syringes with 23g, 1.5" needles already on them, and the 18g needles separately. It seems more cost effective to buy the syringes and needles, and just switch out the needle tips when I draw and inject. To clarify: the syringe comes with the 23g needle; I would take that off (without removing the plastic cap over it) and replace it with the 18g, then draw up my T and switch that back out for the 23g, and inject.
Good/bad idea? Has anyone done something like this before?

Also, does anyone have tips/tricks for painless (or at least less painful) IM injections?