Just seen this thread, been busy all weekend, but what a great idea. The Haynes Roadster scene is big enough and getting bigger to warrant this....
A section could also be dedicated to development of the single seater, would be good for people to see and attract more excitement and interest. There's loads you could put in there if somebody has the time to do it.
I believe £10 a year would be more reasonable / realistic, i'm sure most people have had experience of how costs can spiral for things projects that you think wont cost TOO much, especially if you call into B&Q for a few bits.
Go for it.......AndyH