The NC Dept of Agriculture does offer soil testing for residents.  Samples submitted from April 1 to November 30 are free - from December 1 to March 31  there is a $4 fee for each sample submitted.  The soil testing lab is at 4300 Reedy Creek Rd, Raleigh, NC.  Sample boxes and forms can be picked up at that location on the loading dock or in bins outside the entrance to the Wake County Extension Office - 4001-E Carya Dr, Raleigh, NC.    Results will be emailed to you.  The link below provides additional information on sample collection and completion of forms.

https://chatham.ces.ncsu.edu/soil-testing-for-lawns-and-gardens/