This pedal powered pickup is available from tricycleweb in Holland. Delivery to UK addresses is a rather hefty €405 on top of the not unreasonable €299.95 asking price. The pickup or rather " model 060" has a huge (1000x630x290mm) load box which can carry 150Kg and has an unladen weight of 55Kg. The 060 doesn't appear to have derailleur or hub for gear changing so your stuck with one speed. In my case I suspect this would be stopped!
Indeed stopping might be interesting in itself. The 060 has two brake levers acting on two ordinary looking brake blocks on the 24" front wheel via a rod connector. Additionally there is a parking brake acting on the 26" rear wheels. The frame of the pickup is fully galvanised and you can have it in any colour you like so long as it's black. Coming flat-packed means that you'll have a fair amount of assembley work to do but there are many detailed photos on the web site to guide you through it. Though the 060 doesn't seem to have a load cover and is lacking in the braking and gearing departments it still makes an inexpensive alternative to the "Cargo Trike" from Cycles maximus (pictured bottom) which has a 258Kg payload capacity with 3x8 gears and a £2795 price tag. In fairness though, the CM offering is a much better thought out and engineered vehicle.