Try Amazon! 
Yea, a real dealer is the best way to go. Do a lot of research on good brands and service in your area. So much stuff is made in China garbage you want to avoid.
If you see a local yard crew about to start mowing a yard, stop and ask who is the supervisor and ask him where the yard pros buy their equipment. Ask a few different crews. Likely there is one place that is the most popular for the pros. Go there to get pro level reliable equipment and service if needed.
I can think of three places here that specialize in sales to yard mowing companies.