Attorney fees if seller backs out of offer

What is the likelihood of this being a problem?

SE, why?

noobienoob,
Generally speaking, at least in Manhattan purchases, your (the buyer's) attorney likes to say they do "half the work" before and including signing the contract -- this includes things like due diligence, reviewing the received contract, communicating with the seller's attorney if necessary, etc. If you have a decent, down-to-earth lawyer and are on good terms with him/her, if the contract is not fully completed, more often than not they will charge you 50% of their flat fee (if you are dealing with an attorney that you have an hourly agreement with, this may not apply, and they may just charge you based on hours, which can range greatly). This is not a hard and fast rule, but half of your total owed amount, give or take, is what most (decent) flat-fee-based attorneys will ask for, if a deal dies before a contract is completed.

i guess it depends on the attorney. my attorney told me that he would charge half at mid-point and at closing.

This happened to me, and I had to pay. Annoying, to say the least.

I agree that it depends on the attorney. I had one that charged me for every phone call. Another which I used for a buy and sell charged me one fee although although it took over a year to get both done and multiple back and forth with the lawyers. I think my lawyer felt that if the deal fell through, I would probably find another apt and use him again so he didn't bother billing me.

Well done for researching, as this does happen.

I usually like 3 tiers.
1. If just a contract has gone out, and there has been a call or two. (nothing we are both taking a risk, the lawyers risk is to get the business)
2. If it doesn't happen from past midway to closing ($1000)
3. If the deal gets done. ($2400).

This motivates them to be responsive and get the done deal.