It depends on what type of unit you mean. If you are talking about phalangitai, they usually wore a linothorax, a Thraikian or Phrygian helmet, an Illyrian shield, one or no greave, a sarissa and a shortsword. This type of equipement would not be very expensive, as opposed to a legionary for example, but in great numbers it would be a great amount of coins. Do not forget that those weapons needed constant friction and care as to prevent them from rust and such things.

The equipement of mlight and medium infantry would be given by the state, AFAIK, though aristocrats or wealthy citizens could provide their own equipment in battle, fighting as heavier units. Peltastai or Thureophoroi could also have been equipped by the state, as well as the psiloi regiments (toxotai, akontistai, sphendonetai).

Maion