I will go for option 2.
As you mentioned, it is a new domain. No point doing a 301 redirect for a brand new domain name unless you are using it as a buffer site.
Also, I don't think there will be many people typing in "cellphonerepairlancasterpa.com" directly into their browser in order to be redirected to your client's site. Most of them will probably type in "cell phone repair lan caster pa" instead.
So it is better to get the domain ranked. Also, if it is a low competition keyword, no one is stopping you to get 2 first page listings. You can ranked both the new domain as well as your client's original site for "cell phone repair lan caster pa".