How do you handle comments about how expensive your service is?

Speak to the benefits of your Tow business Insured, CDL, Vehicles...
People only talk price cause they do not know what else to talk about.
There is also the "Answer their question with a Question" because the one asking the Questions is the one in control of the conversation.
Be prepared to ask 3 questions.
Year Make Model?
Plate, VIN or mileage?
AWD or 4WD?
Distance needed to have vehicle towed?
Whatever. Just do not see price as a negative question.
Good luck

a 100 mile tow for $500.00 is cheap, inn the Hamptons, a tow from accident site-toyard-our shop can be $500.00

Good Morning, 
I have found that once you have a reputation for providing top quality service that the cost of your service becomes less of the topic. Oftentimes you have to educate your client on what it is he or she may need and show them all the benefits that your company brings to the table. 
 

never under charge for your services 

I don`t thats the price, sometime I explain the cost but not usually

Customer satisfaction is everything, you always need to keep your customers concerns in the fore front your repairs and updated conversation as to the down time of their vehicle . This keeps them in the loop and involved. As a Service manager for 3 Car Manufactures over my 40 years in the business and the recipient of several service manager of the year awards for CSI (customer service index),it is not to brag but to let everyone know that it works. Customer Satisfaction is key to profit and recurring customers.
 

You always have to be upfront and honest. An accurate estimate of services is essential.
You have to sell not only the product but also your expertise. It costs money to get the service done correctly the first time. If you make a mistake you make it right. This will save your customer and make them realize you are an honest business and one to do come back to for your future needs.

I also used to transport, and came across this regularly. If your pricing is in line with your competitors, then you can always recommend a customer call around for quotes to check your pricing. The trick is, of course, to sell them on the value of using your service while you still have them so they are confident to call you back because there will always be someone cheaper, or you're doing something wrong. I think the most important thing for a towing company is to make a customer feel comfortable the minute you answer the phone, sound professional and understanding, since you don't know what their situation is before they have a chance to tell you. Also, remind them of your costs and what they are paying you for, not just to tow a car, but to take care of them so they don't have to worry. That's just my two cents!

we offer free mobile service to the customers home or work place.   We route our daily jobs to maximize our speed of service and to be as efficient as we can possibly be.

All things are more expensive, It is costly to care for people in a community ther are more expensives then the public understands