Damage to Aliminium dinghy. Any idea of cost??????

Took the tinney up north went over miles of really rough tracks travelling way slower than most other boats but still came back with some  cracks in the hull. Both are on the bottom of the hull where the rear of the back side skids meets the boat....the central rollers had dropped due to vibration / weight from load.  I figure they will need a 100mm patch on each side. Anyone have a rough idea of what i can expect repairs to cost