Is there a cheap way to fix this Leak in my radiator

The cheapest way is to do it yourself

Would it be possible to put a type of sealant from the inside of the crack?

You mean something that would plug up small openings ? The coolant system is full of small openings , are you sure you want to do that ? Replace the radiator

Don't put any kind of sealant in the radiator!! You will clog up the cooling passages in the engine and the heater core!! One thing you can try is black pepper. The kind you sprinkle on your food. It will not dissolve or clog up your cooling system passages. But it will find its way to the leak and plug it up. That's a Depression era trick! You can also try, with the engine cold, JB Weld on the outside of the radiator. Make sure the area is clean and dry before applying the JB Weld. Let it sit for 24 hours before you refill the radiator and run the engine. I've had good luck with JB Weld so I think it's worth a shot! Also, check Ebay for an inexpensive new radiator. I just bought one for my S10 Pick Up for $78 and free shipping! Hope that helps! Jim