The RocketReviews.com Deals Finder currently shows that Amazon currently has bulk packages of 24 Estes C6-5 motors listed for $27.31 with free shipping. That’s more than $65 off the list price. Look for Amazon’s offer under “More Buying Choices.”
The catch is that Amazon is listing them as “Not in Stock.” But, they are accepting orders at the low price and promising to ship them later. So, I’m not sure if you’ll receive the motors at the low price or not. But, it’s worth a try.
9/24 UPDATE: The Amazon offer no longer appears at Amazon.com.