Community garden supplies (Observatory Hill, Cambridge)

I help organise a small community garden. Acquiring some of these for free would help us stretch our budget:
- tomato cages (any height, but especially tall ones)
- large pots (>15 inch diameter, bigger the better; any material including fabric)
- seed starting supplies (particularly grow light and heat mat)
- chicken wire fencing (to keep out bunnies)
- nitrogen-heavy fertilizer