I think I have worked it out. 1.50 on low numbers and 1.00 on 3rd dozen, so the progression would be 2.50, 15.00, 77.50
Which is far too risky as Ive seen zero repeat 4 times before...
But possibly use the bet to try and win a few 0.50 and if it loses then wait for a string of low numbers then bet 3.00 on high then use martingale?