Hit your local AutoZone or Advance auto parts. The cheap ones will do the same job as the expensive ones and I find they pretty much last forever as long as you don't drop them or break them outright.
One thing about the more expensive ones that is nice, but not necessary is that they have an advance feature built into them, so that you can keep the mark on the crank pulley lined up at the zero mark, but still be able to tell where the timing is at. Some also have a tach built in too which is handy.
"Free advice is worth what you pay for it."™