Pontius,
I was going to suggest Westland rather than BWOS - Somerset's finest make several devices of different sizes, which comprise downwards-blowing fans which can, on occasion, lift themselves (but not much else) into position and maintain station for many, many seconds before running out of fuel or developing a fault.
Potential buyers should note that these devices are aimed at the luxury/connoisseurs' end of the market and are priced accordingly. The exclusivity of the brand would be harmed if they were sold to any old operator.
3 years' (or 30 flying hours, whichever occurs first) free servicing and 0% APR not included. Terms and conditions apply. Figures incorrect at time of going to press. Metallic paint extra.