Raisers may be asked to take over the process with an older dog. This depends on the guide dog school. Pups may return to the school for evaluation and training at between 12 and 18 months of age. The average is 14 months of age. This also depends on the school.
Some programs pay all costs, or reimburse for only certain things, like vet care.
Many vets will give discounts to puppy raisers though. If you've never raised a puppy before, the most significant cost could be in that all too familiar puppy damage caused to your home and property. That damage you laugh about years later. The most common breed used as a guide in the United States is the Labrador Retriever. All colors are used in this breed.