an electric fence.
the most expensive part is the charger. for a smallish bee yard, you can get a good charger like this http://www.horse.com/item/parmak-field-master-2-charger/BXJ04/
and it will do the job. posts, wire, etc. are not very expensive.
mow lawns, have a bake sale, sell some games
please keep us informed about how you are doing. it's great to have younger members. you are the future of beekeeping!