Is there a way to change all of the customers' price codes to the same number at the same time?  The purpose would be to avoid several hundred separate entries.
Thank You.

Yes, use UT-K-B, file BKARCUST, Field BKIC.PRICE.MAT
 
 
If you want to change everything regardless of its current value to some new value, then when it asks for the value to replace, leave it blank (or 0 since it is an integer field) and answer Y to replace all values.  Then enter the new value to replace with.