For collectors who still have some pennies rattling about in their piggy banks, buying online is definitely the way to go. And like it or not, eBay is still the number one online venue for buying and adding to a cookie jar collection. There are good sellers and bad sellers, so do your homework, know your jars, and ask questions of sellers if their descriptions are not clear. When money gets tight, some sellers get "looser" with their descriptions. It's far better to know "a small crazing line" is in fact the beginnings of a hairline crack before you bid, then after you receive the jar and have to make the decision to return or live with it.
In addition, there are still a lot of fake and reproduction jars out there on the market. If you don't have an extensive library of reference books or unsure of a jar you want to bid on, then ask questions in the cookie jar forum. The vast majority of seasoned collectors are more than willing to help newbies because they understand an influx of new collectors into the hobby is a good thing. Terrific, in fact, because without new generations of collectors there will be no one out there to buy jars and this wonderful hobby of collecting cookie jars will simply fade away. Remember Beanie Babies? Okay, not the greatest comparison, but you get the point.
This brings me to the subject of friends and collecting, because the two go hand in hand. We've made some terrific friends since we started collecting cookie jars. Friends we know will last a lifetime because our interests and commonality go well beyond just the world of collecting. They are the true jewels in our collection, so don't be shy. Get out there and meet your fellow collectors and don't worry if you collect different jars than they do, have a small collection, or a limited knowledge of cookie jars. Everyone was a newbie at one time and the very best part of being a collector is sharing your collection with others.