I’d say you were on a hiding to nothing looking for a cheap second hand Bummy anytime soon. Most of us who now have them waited for nearly a year, calling our LBS’s every couple of weeks until we finally got one. Sheffy went to California to bring one back. There are only a couple of dozen in the UK, tops I think. @In addition, the price of them new has gone up Â£150 for the frame since they first came. Sorry to just give you bad news, but unless anyone bought one, hates it and desperately needs some crack or a new kidney I think you’ll struggle to get one for much under new price.
That said, as the others say, the Kona Ute is a decent bike and a lot cheaper. The Yuba is cheaper still. I think it’s right to say that the Yuba’s are sold to guys in Africa who don’t have a car more than to middle class hobbyists in the UK, so I reckon it’ll probably be alright for the sort of off-roading that you can do on a bike of that length and weight.
The other thing to take seriosuly is the Xtracycle conversion. That let’s you convert your existing bike for about Â£400, and you aren’t stuck with it if you then don’t like it. I started off with an Xtracycle conversion while I was waiting for the dummy. It’s fine, really works well. The dummy is solider, but is not fundamentally better I don’t think.