Since you are a cash buyer I would expect a range of 500 to 1000. Don't forget your title insurance too. 100 % equity should be protected by title insurance.
You should call around after getting some referrals and make sure you know what he/she will do for you.
Just like a good agent is worth every penny you spend so is a good attorney. You need good representation and that should be your focus not saving a few hundred dollars. The attorney you pick could save you more than what it costs to use his/her services. I would call a few and find one that has done many real estate closings and ask for references.
All the best,
There is no set amount but you should expect to pay between $500-$1000. Make sure you get title insurance to protect your 100% equity in the property. I have a good referral located on my website under preferred partners.