Lee, what about a round one for front mud guards, something like this maybe?? Just a thought?? Might not be cost effective.
I did think about doing the alternative logo off the t shirts etc - http://northwestbikers.spreadshirt.co.uk/men-s-t-shirt-black-yellow-A13422746/customize/color/2 But it would depend on numbers as I dont want to be forking out a load of my own money to end up stuck with them.