Offal meats (beef liver, kidney, heart, chicken heart & gizzards) where I live is SUPER affordable/pound (only $2/lb in most cases), and because I only need so much to create an overall balanced meal over time, it lasts awhile. Other local butchers around here GIVE them away.
You can get chicken thigh, wings with bones for about $4 for 3 lbs here. Look for sales, it's really quite affordable.
I found a grinder on Craigslist for $20.
I buy supplements (taurine, vitamin B complex) for $5/each at GNC or local drug store.
Eggs are cheap... if you can, find someone with chickens who sells their own eggs... I used to have chickens as pets when I was a kid - even 10 produced too many eggs we could eat in a week and ended up selling them to neighbors for $1 a carton, etc.
I live on the coast...minnows and mackerel are READILY available to me to fish for myself, or available for cheap as "bait fish" in lobster pounds, bait shops, even the local supermaket fish section might have some for sale. I don't give fish often or in large amounts, but I much prefer feeding raw fresh fish to adding fish oil, so..... gosh, even a can of sardines if you're really desparate runs about $2/can and contains tons of good stuff - get the no salt, spring water kind.
Even though it's time-consuming (I find it fun, personally) homemade raw is, really quite affordable....... more so than canned high quality commercial.......... I spend about $30 a month on making cat foods.... a dollar a day.... is this really too much???... :/ .....