How much does it cost to have two kittens and thier mom in ur house per week?

i have a summer job and i was wondering if i can pay for some of their things like food and stuff they r strays no am not giving them to a shelter cuz there is no animal shelter rescu group or any thing i hope animal rights comes stray cats stay stray and stray dogs get shot and cats get mostly run over by car or attacked by rocks my moms cat when she was a kid they put her on fire so i want to save those kittens and their mom and yes i will get all of them spayed spayed cuz they r all female calico