Hello Catnip!
My two are on whiskas kitten food as this is what the breeder was feeding them. Initially, like you, I thought to buy them cat food with a higher meat content, but they seem to be doing well so I've kept them on the Whiskas. They eat a tremendous amount of food. Not sure if this is just the typical bengal appetite or because the meat content in the whiskas isn't very high.
Simba and Flick eat around 6-8 pouches a day between them, which works out at around £20 a week, give or take, (depends on when their food is on offer).
Then there is the cat litter expense to take into account as what goes in certainly does come out again, and as they are indoor cats I scoop a LOT of poop and get through approximately 10 litres of catsan litter a week, which works out at around £10 a week.
So for my 2 cats, this works out at around £130/month for food and litter in my house.
Dry food seems much cheaper and there is one brand which says it contains 80% chicken/salmon content. I think it was called "applaws" or something like that. Saw it in "Pets at Home" store.
Anyways, hope that helps.