blown head gasket/ or seal

i am considering buying a 92'jeep cherokee sport, but I had friend look at it and there is a lot of oil on the side of the engine. I was told it was a blown gasket.... how much should that cost to repair? I would just like to know since I am a single mother and really cant afford the repairs if it too much. The od meter is 178000, automatic, 2wheel drive. and making a ticking sound in both motion and idilng.
I cant donate anything now but i can on the 25 and will be glad to send someting to you , i just really need help now.
Thank you.
Tammy