I have been looking at ways to get free timeline pictures, and I saw this idea that I thought was FABULOUS...
Get your hands on an old set of encyclopedias (the age doesn't matter since most of your timeline figures won't come from the past 30 years!), and use them to cut out pictures! I'll bet a lot of what you might want would be in there. And Bible figures (that might not be in there) are pretty easy to find online.
If you don't already have a set, you could probably find some at 1/2-price books, your library (if they sell used books), or freecycle.com. Now, if I could only get my parents to let go of their 1980 World Book set.... They would be HORRIFIED if they knew I wanted to cut them up!!
