I've learned this year more than ever to stand firm on price. Like Mow Ed said, offer something that others can't. Pay your insurance, work comp, taxes, etc...and charge accordingly. I'm the same way when it comes to recruiting new business too. If someone says they are happy with the company they have, I tell them that it's good to hear that they have a company they are happy with and that they are loyal customers. Unfortuneatly it doesn't happen enough in this business.
I have received calls from two customers this year that were seriously POd at their current provider. This provider is a huge player in my area, several million dollar operation. The one account is a good $30k / year for landscape maintenance + snow. The other is just an average sized commercial account. Both of these customers said that their current company wouldn't call them back after several phone calls and continued to get more outrageous with their snow billing. Both customers had been with the company for several years.
These are the accounts I want. They aren't price shopping, they are service shopping. You know you don't have to kill your margin to gain revenue. You charge what you charge and give them the service they expect. If you do that, they will be loyal to you and won't be taking the next bid that comes along and switching over some ridiculous amount.