I actually gave the cheap one a chance at first, it wouldn't even fit right, I had to hold it in place using some folded paper on the sides it was a complete disaster and went straight to the garbage can
I asked for the OEM one at VW, they said there isn't one made for Lupo, I gave them the part no. Mobieus_uk posted and bingo. Costed me 67 euros, imported from Germany, took 3 weeks. I still find it sad that VW couldn't find that themselves.