Ft. Sam's shop has a good selection for all the branches. Couple pieces of advice: only get the alterations done on post which are covered by the purchase price. Anything extra, get done on your own from one of the many little cleaner/tailors close to the post. Don't get pin on insignia for you BDUs. Buy the sewn on ones and take them to one of the little shops. They's make you your name tags (both for class Bs and BDUs) as well. In terms of your class A Uniform, HPSPers are not eligible for the National Defense Service Medal until they are on permanent active duty. Thus if you didn't go to OBC you won't need to worry about ribbons on your Class A uniform.
Ed