Serious note here. Last time I posted this article about a compatible Manfrotto Quick Release adapter on the cheap, it sold out around the world. Yes this includes Europe as well. The hype died down when prices went upwards and the item was rarely in stock. You can say that the stars are aligned once again, because not only are they listed as 'in stock', but there's also a nice little discount going on too making it a great buy again. Perfect to stay compatible with your Manfrotto tripods, these QR adapters are great for your new Jibs/Cranes, Sliders, Steadicams, etc. Before they run out of stock again (I'm positive they will be out of stock again), you might want to check out the current price and inventory (below).
If you're just in need of the plate itself, they have that available too (again not stating Manfrotto Compatible)
Sliding Plate (not Manfrotto branded)