The risk of getting AIDS and other diseases from a blood transfusion is very low. Autologous blood transfusion, or transfusion with a person's own previously donated blood will completely eliminate this risk.
Many blood banks allow people to donate their blood for only their use.
The blood is stored for elective surgery or a medical emergency. This blood is not part of the general blood supply for donation to the public. Insurance does not always cover the expense. The expense is for the extra work involved in the special labeling, separate storage, and delivery at the right time. The added cost is worth it to some people.