Don't let all the blowhards on this site make you think you are in the wrong for asking this.  I had almost the same situation happen to me a couple years ago.  Same deal, relatives who didn't have the guts or the common courtesy to give me, at the very least, a phone call let alone a face to face conversation.  They had sent the email the night of August 31st saying that I was no longer renting the farm.  Being a holiday weekend I didn't check my email for a few days so I didn't even see it until after Sept. 1st.  I drove over to their place to get an explanation and to tell them that technically their email didn't really constitute notification and that if I wanted to be difficult I could probably farm it one more year at the previous years price as was stated in our contract.  I never really had any intention of doing it when I said it.  It was more of a statement about the principle of the matter.  They got all pissed, started yelling and cussing at me.  When that happened politely said you may hear from me, you may hear from my lawyer, and walked out.  I never really pursued it even though I could and probably should have.  I digress...my point is that if you really want to go after them and your previous contract had auto-renewal clause in it you can.  An increase of $50 for the coming crop year is insane.  If I was in your shoes I would have a hard time paying that unless its prime ground.  Try talking to them and telling them that if you want you can farm it another year at least years price.  Feel them out.  If you're not going to pay them that extra $50/acre you have nothing to lose.  And don't let the high rent groupies on here tell you that you should have been paying more the last few years and how dare you rip off that poor landowner, that's BS.  Good luck.