I use Cahill's. In my opinion the price I pay is decent and my lawn looks great. 2 or 3 years ago(don't remember exatly), I went with a "cheaper" service and got exatly what I paid for. By the end of that summer my lawn looked like $&!T. I was basically paying someone to destroy it. Well, lesson learned... I paid the little extra (which wasn't relly that much anyway) and by the beginning of the next summer it was back to looking great.
If you end up doing it yourself, check out Purdue's website. It has a great calendar on when to apply the treatments. The key is to be proactive and not reactive. You may have to adjust the calendar since it was a really warm March