Agility course won't reduce its cost?

[Enfyny]

So, as in mentions in the description, if you build a course its cows will be 10% lower but for some reason the price is still the same after me tryting to build and destroy it for a couple of times

[Dwane Dibbley]

There is like 80 or 90% cap (which can be increased to 100% late in the game).

EDIT: from wiki

"Each time an obstacle is constructed, the item cost to construct the same obstacle again is reduced by 4%. This bonus can stack up to 10 times for a total of a 40% reduction in cost. This does not reduce the GP or Slayer Coin cost to build obstacles, but can be combined with the Mastery Unlocks and Agility Skillcape to further reduce the Item cost to build or rebuild an obstacle, up to a maximum of 95% cost reduction (or 100% once the Agility Item Cost Reduction Enhancement upgrade has been purchased),

The GP and Slayer Coin cost of obstacles can be reduced by a maximum of 60%. 30% reduction from the Superior Agility Skillcape, 20% reduction from achieving 80 & 95 mastery on that obstacle, and 10% reduction from the 50% mastery pool bonus. "