I fix cracked plastic pots with duct tape or Gorilla Tape.
If they are still fragile, I save the broken ones until I have two of the same size. Then I nest them together with the cracks opposite each other, and that double-pot is usually strong enough to get more use out of them.
Some nurseries and even big stores will throw dirty pots into a bin somewhere and let customers take them home. You may have to ask around to find out where it is, or get on a manager's good side to access their stash.
The only two ways I know to get on a manager's good side are to buy more things, and flatter him/her.
