I agree totally with Liebherr1160. A boom truck is a less than reasonable option for what you're going to try to use the next 'crane' for. Boom trucks have their place and should stay there. I don't run many lighter taxi cranes so can't offer much in the way of a suggestion but do a good thorough inspection of the unit before paying up or you might be sorry down the road. I was a crane inspector for a few years and can tell you that a lot of structural damage can go unseen if you don't look past the fresh paint and new tires. Get all over and underneath it with a good light, check out the maintenance history, fluid change intervals on key items and maybe even send in a fluid sample for an analysis, look for signs of misuse too. Good luck.