There's several types of chests and chest-like storage media.  These
vary in cost, and can be purchased from player merchants.  See "help spell
create chest" for the costs of creating these, and ask around for going
rates.  (Specialized chest-like things, such as wand racks, can be created
by other guilds.  You'll catch on to these over time.)
     Chests must be stored in a castle room to keep eq through boot. 
Castles are all player-owned, so you have to find a player with a castle if
you want a room.  Most players will charge you rent - at least the cost of
maintaining the castle, usually plus a profit.  Rent is extremely variable,
so you'll have to ask around.
See also HELP CASTLE and HELP BOXES.