Nice simple idea. Check out this one I found on google images. It is a mech hanger bolted to a piece of metal bolted to a jockey wheel(at least I think.)
I would get a Monty 221 pr for £197 or for £230, just a little over your budget, a 2008 echo lite. Hope this helps. http://www.tartybikes.co.uk/product.php?pr...;category_id=36 http://www.tartybikes.co.uk/product.php?pr...;category_id=36