If you are unable to buy a suit at this time, borrow one from a friend. If you are unable to obtain a suit, a conservative sports jacket and dress trousers are second best. Solid light blue is an acceptable alternative. If you do not own either, buy some. There is no short cut here, and if you get the job you will probably need more than one shirt anyway.
Silk ties knot best so are worth the extra cost.
Shoes Shoes should be brown or black polished leather and in good repair. Stay away from styles which include buckles or chains. Never wear white, tan or suede shoes. Socks Wear comfortable dark socks. Depending on the outfit use black, dark gray or dark blue.