Getting an entertainment lawyer isn’t hard to do – just do a Google search for “entertainment lawyer” and look for a few in Beverly Hills and you’ll probably find a few good ones. You’ll want to ask them if they have experience with screenwriting option/purchase agreements. Assuming the option/purchase agreement is pretty standard it will probably take them 4 hours to look over – more time for more complicated agreements. Any decent entertainment attorney is going to charge you $250 – $500 per hour so you’re looking at spending probably $1,000 to $2,000 for them to look over and advise you on a basic screenplay option/purchase agreement. If there is a lot of back and forth with the producer it can get quite expensive.
So you don’t need an entertainment attorney unless a producer wants to option or purchase your script. An entertainment attorney isn’t going to act as an agent and send your material out and try and find you work. They’re simply going to handle your legal issues and charge you on a per hour basis.
If you have an agent or manager they probably have a lawyer on retainer who handles legal issues on contracts that you’ll be signing. So if you have an agent or manger you probably won’t need an entertainment attorney, at least not one to handle your option / purchase agreements.
For advice on finding an agent check out my post How do you get an agent for your screenplay? (And why you don’t need one!).