Stop at your local Fire Department ask them who maintains/tests their SCBA tanks.... if local take yours' there. I have a local fire equipment retailer/maintenance company close by, just had my tank hydro tested in August, $45 included fill.
My local dive shop was three times what a a fire extinguisher shop was. And they told me to go waste an hour and come back and it will be ready. Check around your area. Typically dive shops send their tanks out so justifiably they tack on an upcharge for their efforts.