|Egg Carton Method|
The plastic egg cartons can potentially be reused. I think my wife actually bought some eggs in this carton last week, so I'll see how it does.
Update: The egg carton method didn't seem so promising at first, but as of today I have quite a few seedlings sprouted.
I really like the plastic bag method. You take a paper towel, wet it down, place your seeds on it, and then put the paper towel inside a ziploc bag. I like doing this, I can make a ton of these very quickly, they are relatively cheap, and they can be stacked in a warm dark place out of the way. I've had good luck with these in the past. The bags can be reused for years, and they take up no storage space.
Toilet paper rolls
|Toilet Paper Roll Method|
Bonus: Potting Mixes
A long time ago I used to keep various species of Reptilia in terrariums, and one my of my favorite seed starting mixes comes from this era.
1 part ground coconut husk
1 part partially composted leaves
Just mix it thoroughly together, and add water. It will hold moisture for days.