I am reprinting a letter that Heros Von Borcke (Assistant Adjutant General) wrote to Aide-de-Camp R. Channing Price. (Von Borcke's spelling was atrocious, so I've cleaned it up) It lists the equipment that Price must have to be a member of Stuart's staff.
Equipment Suitable for An Officer of Cavalry:
A good horse which can be bought in Richmond or among the regiments. The cost will be between 400 and 500 dollars.
A good Jenifer saddle and bridle, which can be bought at the ordinance store for 62 dollars.
Arms will be sabre and pistol, which will cost from 80 to 100 dollars.
A uniform trimmed with yellow (cavalry) or buff (staff) either coat or jacket 80 to 100 dollars. (An aside -- the jacket was called a shell jacket, but Stuart affectionately called it his fighting jacket)
Good cavalry boots with spurs, 50 dollars.
Gray or black hat, 15 dollars.
Saddle blanket and other blanket, 20 dollars.
Oilcloth coat 25-30 dollars.
Several little things not mentioned (little valise, comb, brush, etc.)
So to be a cavalry member the initial outlay was anywhere between 732 and 877 dollars.