Surround sound for cinema feature film (Pricing of Dolby Surround)
If your plan is to deliver the end product as a DCP, you don't need any Dolby licensing or approval, you can just deliver the theater mix as a 6 discrete channels 5.1 mix in the DCP container.

Nevertheless, you will need an experienced sound mixer and appropriate dubbing theater. Budgeting the audio production and post-production will depend on many factors and the help of a sound person might be needed.