The Google Distance Matrix API has been deprecated and is now replaced by the Compute Routes endpoint of the Routes API (https://blog.afi.io/blog/using-the-google-distance-matrix-api-for-taxi-dispatch/). This API costs $5 CPM per element so if you have a 25 origin x 25 destination it will cost 10 * 10 * ($5 / 1000) = $3.125. You won't be able to do a single 2 x 1000 call because the max number of origins and destinations is 25.