Congrats on deciding to join the rank of grey owner, you are in for a treat of a lifetime.
Its not cheap to keep an african grey, they need a big cage, toys, playstand, travel cage, good food, vet visits and a certain amount of your time. Cage will be a one time thing but the other things will be ongoing and could vary from time to time.
Most of us usually take our grey to see an avian vet for an annual checkup but if something happens to your bird or it gets sick then that is additional money.
Most of us feed our greys some of what we eat, vegetables, fruits, seeds, nuts, legumes and a little chicken or other meat occasionally. The main expense foodwise is the pellets you should provide at all times for snacking.
One book comes to mind if I only mention one is "For the Love of Greys" by Bobbi Brinker, it has a lot of good information that covers all areas about the grey.