Training: Spears vs. Royal Spears
This means 3 spears will break in 200 seconds, and 2 royal spears will break in 200 seconds (2 second each attack)
This means: With 100 spears you can train 6660 seconds, with 100 royal spears you can train 10000 seconds. => 100 spears = 111 mins, 100 r-spears = 167 mins => 100 spears are 2000 cap and 1000gp, calculated down you need 66 r-spears to train the same amount of time, thats 1661 cap and 997 gp
If we compare the cap you need you will see: 2000 cap = 100 spears = 111 mins, 2000 cap = 80 rs = (and now the interesting part) 133.6 mins!
And 111 mins training with spears = 1000gp, 133.6 mins training with royal spears = 1200gp => 1000/111 = 9.01gp/minute, 1200/133.6 = 8.98gp/minute
If you want to stay longer at training, it is better to use royal spears, its even a little cheaper.