costs us about an average of 40 dollars a month to feed our rats... we have some where around 80 females, 10 males plus the ones we're fattening up, our colony of blues and the 11 rats that got set aside as pets.
for bedding we use shavings and newspaper. news paper is free (so much snail mail spam). and shavings are cheap... about 5$ a month.
now there is some startup cost. my rack cost me ~$200 for the wood and bins, and the watering system was ~$50 from tsc (it's on special order, most of it still yet to arrive).
our cages cost us a fare bit but we sprung for quality ones, we could have made due with less expensive cages but sometimes you want nice stuff
the biggest saver is the watering system, i think it cost 1/3 what our water bottle system cost...
then of course there's the time involved... i spend 15 min a day filling water bottles and filling food bowls (we're in the process of switching to food hoppers). food hoppers are great time savers.
I could spend less and check them every other day, but I like checking on them and talking to my favourite breeders.
I spend about an hour a week cleaning cages/rack trays, though some i don't need to change every week.
Bob Applegate was telling me about some aspen pellets that allow him to go 1 month with out changing the bedding. I'm currently on the hunt for these.