It depends on if you have more money or patience how big of bin and how much food I started with 2 pounds in a big rubbermaid but 250 will work if you have time to let them reproduce

Be sure its not extremly cold when you mailorder the worms

250 worms will become a pound of worms in about 6 months. Don't expect to have vermicompost for this summer's garden. This takes time. I would shop around and find a good price on a pound of worms. You can spend a little more and have a better start. You will be spending $15 for 1/4 lb of worms, when for a little more than twice the money you can get 4 times the worms.

A lot of suppliers wont' ship before spring. They guarantee live delivery. In this weather live delivery may not be possible.

Red wigglers (E. fetida) can double in population in 90 days *under certain conditions*. If you're in zone 6, that's going to mean keeping them indoors and probably supplying some heat to maintain 70-77F bin temps.

Like jonas said, time or money. What kind of worms on ebay and where are they shipping them from? Lowest online price from what seems to be a reliable source is $15/lb. + $8 shipping Priority Mail.

Andrew