Recycled jars are cheapest, but if you want 'em all to match (even the different sizes) and need 'em more quickly than slow recycling allows, go to a wholesale glass bottle company (not a trendy kitchen boutique) and you'll be surprised how reasonably you can get a case of two dozen glass jars and lids (in England, anyway). This is also true of larger glass or plastic jars for beans and grains.

I personally use "ointment jars" for spices. They're cylindrical, slightly wider than they're tall, and have caps the same diameter as the jar (see icon). For obvious reasons, unless you have an autoclave to clean 'em and can replace the cardboard insert in the cap, don't reuse jars that have actually held ointment.

Nutmegs are large enough that you can put powdered and whole in the same jar - doesn't work so well for cloves.