How much do you pay per year for your collection?

I spend a little under 4 grand this year on mine, but its worth much much more than that in cash value.

Rodents average out to about $200 per month
Electricity averages out around about $50 per month (This includes using a dishwasher for cleaning bowls and heaters for the room)
Bedding about $20 per month
Equipment upkeep about $50 per month
Other cleaning supplies $10 per month

Total of $330 per month X 12 months = $3960 per year.