My father was building nitro powered planes back in the late 1950's and continued to build them untill he died. As a matter of fact there were two in progress on his work bench when he passed. I shudder to think of the money he spent (and lost/crashed) in his lifetime. I remember about 15 years ago he called me and told me about a plane that he had just finished and, on it's maiden flight, lost radio contact and he had to watch it fly away. He was proud of that plane though, he said it flew straight and true. Amazingly enough, two years later someone found it in a tree and returned it to him (he put his name and ph # in all his planes). It was not in very good cndition but he was able to salvage the engine and some of the electronics. Both of my brothers (and none of us is young anymore) play with nitro (and electric) rc's to this day and my nephews do too.
So I guess my point is that the cost of the hobby is pretty irrelivent when you consider the enjoyment and memories that it provides. I know I'll never remember my dad w/o remembering how very much he enjoyed this hobby.