I've looked it's not going to be cheap going down the Ac vfd route, nothing cheap in ebay anyway. Not ruling it out tho, may just take time to find a cheap setup.

I have made some progress and have found a reasonably priced kb dc controller box.

http://www.axiscontrols.co.uk/shop/kbwm-range/9381.

I think someone on here used a kb board but linked it to the bob. more reading required!