By far the cheapest solution I think would be mine but most likely far from class legal. As I do sail alone majority of the time I must improvise occaisionally having only 2 hands. Has cost me more than 1 tiller bar already so now I use an oridinairy bamboo cane bought at a local garden centre. Available in sizes 9 to 12". I use ± 10". Not always handy but sailing alone seldom a problem. I use a small alu tube with 2 holes to connect the bamboo to the alu tube. Amazingly enough I use common electrical installation wire to lock bamboo to alu. No problems with our extreme salty conditions / can be removed without tools / re-usable and lasting !!! On the other end of the alu tube I use a small piece of re-inforced gas hose as joint to the cross bar. Thus I have an additional flexible connection. In spite of all this I manage to demolish my bamboo creation sometimes but that's affordable. Got spare one at the club and can change in minutes. As said before without tools. Has saved me a lot of money already.

Only 1 remark: in extreme shallow waters - when the ruddders are kicked up - I choose to hold the cross bar till enough depth again. As the rudder blades are not balanced anymore the force might even exceed limitions of my bamboo tiller construction....

Fellow sailers use same system on Tornado...