The cars themselves are not what makes this hobby expensive. You buy a good car and gear ($1400) and spend a couple more hundred on a bucket load of parts for yourself for the year. I reckon you may break an arm or so every few months... then once a year maybe a servo or a diff or maybe even an engine. This is not what kills you in this hobby.
What kills you in this hobby is not the car or racing it. It is the fact that on top of the car and kit, you then need tools, and tool boxes and hauler bags and you try out truggies and then try out brushless and then try out on-road and it just goes on and on.
If i stuck to 1/8th nitro racing i would doubt i'd spend more than $20 a week (on average) for racing. But since i buy new radios, and tools, and then F1 cars and cheap cars to give to friends and family to bash, and so on.... i spend on average about $100 bucks a week on RC.
It's all about the fun though isn't it !!