Most small dings or bends in an aluminum prop can be repaired for a reasonable price. If you do repair, make sure the shop does not file down the blade edges thereby reducing diameter. If your damage includes bites or chunks out of the blade, you should consider a new prop.
Keep in mind that while aluminum propellers can be welded back to look like new, there is significant strength loss when you do. Since a light tap could then put you back where you started from, you shouldn’t spend money on an expensive repair. Stainless props cost more to repair than aluminum because the material is more difficult to work with, however, once properly repaired, they can be almost as good as new.
Another option is Piranha propellers ; they were developed with three things in mind: durability, performance and affordability. A key feature is that the blades are replaceable. You can change the diameter and the pitch, save on the costs involved with propeller repairs, not to mention the potential damage to your gear case. With Piranha you can have some spare blades in the boat for a quick and affordable repair.