The BMW warranty extension cost will vary. Purchasing a warranty directly from the factory is the most expensive route to take, although it may offer more peace of mind to some buyers. The factory warranty extension costs around $2500 to $3000. Third party warranty providers tend to be much less expensive than factory warranty prices. These companies may be able to sell you a warranty at up to 30 percent discounts. However, the reputation and reliability of the company must be taken into consideration when choosing a third party warranty provider. Dealer warranties are cheaper than factory warranties, but require repairs to be made at the dealership and do not allow for repairs during travel.