Pricing yards like that is difficult, especially as a solo operator. I would advise you to stay away from that size no matter the price. Once your business grows and you have over 20 customers and they all want their yard cut just before the weekend, then that will be the lawn you despise going to every week, even if it is reasonably priced. Its absolutely draining to mow a property like that by your self, especially if you're using a walkbehind like me. Wait until you have enough yards that you have to hire someone to help you before starting on lawns that size.
The other thing is location. If that were TX, I could easily believe that someone cuts that lawn for $50 or even less. You may heard about our immigration problem and there are some people willing to do work for far less than others and in some cases they even do a great job. Hard to compete with that....