I have a used Crosby saddle that has a crack on the side of the seat. When I bought it two years ago, I don't remember it having a crack. It's jagged (so it's not a cut) and measures about 2-3 inches.

Does it need to get repaired? And if so, how do I find a place to do that? And how much should I expect to pay?

 If your saddle has a crack, that probably means the leather is very dry. If you used some products like Leather CPR, it would moisturize and soften the leather to prevent cracking in the future. If you find a leather restoration shop, you can bring your saddle in and ask for an estimated price. If your saddle is in good condition over all and just has that crack in the seat, you could get a seat saver made of sheep skin or other materials.