It was outrageous. They eventually dropped the charge along with the ability to pay in store.
This is true even if the check is for, say $10, or even just $2.
AFAIK they still have this policy today.
The strange thing about verizon was that they wanted to charge a fee when there was no apparent prompting, for one of the more convenient (for verizon as well as customer) methods.
Verizon can take have 2-3% more money by convincing people to pay by check/ACH rather than eating the unnecessary cost of credit card processors. Probably would have been far less backlash if they stopped accepting credit cards altogether.
I got around that one: added the checking feature, and wrote myself a check for the entire balance. Voila!