The Commission may enter into and make arrangements with the National Capital Planning Commission or other federal agency or with representatives of the State of Virginia or with other official corporations in Montgomery and Prince George's Counties, relating to the acquisition, development, or improvement of land and other property within the metropolitan district for the purposes specified herein, or any of them. The Commission may not obligate itself or the metropolitan district for expenditures beyond the amount of funds in its possession or to be available to it from bonds, taxes, donations, contributions, or appropriations as provided for or referred to in this article.