My club's training days and camps are significantly cheaper than the National Academy (half the cost or less) and we're fortunate enough with our venue to offer an hourly rate that is smaller than yours (much smaller if they take full advantage of the sessions open to them). Yet this is still too expensive for some.
Participation is important as Sport England give out money partly on this basis. There are many children that would like to fence (it's sword fighting - who wouldn't want to do it?) but can't because their families really can't afford it even when there are relatively inexpensive clubs around. An easy way to boost participation numbers would be to somehow get these kids involved on a regular basis. I don't know how to do this other than venues, coaches or both making themselves available for free. I've tried coaching as a volunteer and I simply can't afford it.