Ralphyhp, you got robed, big time...
Just kidding. Usually, red cap does not command such a price, since it is relative easy to grow (I have problem with Montipora in past two years... don't know why..., but all my acrops are doing well.) In fact, you can get frags for about $10 to $25 easily. However, it is very rare to get a relatively large colony of red cap in such good condition, and it is well worth the price you paid. I hope it is aquacultured one, since they usually do better with wild montis.