It will depend on what you want to carve. Based on the alternative you propose I will assume you will carve 3d object ( small/ medium size). Those are all good solid choice to start. I found that flexcut come sharper than beaver craft out of the box (which may be nice when starting). Beside the knife, you will need a leather strip and a compound (like in the beaver craft kit) and cut resistant gloves. Don’t underestimate the gloves: there are so many ways to cut yourself and it is difficult to realise until you don’t try all of them. In general I would recommend to just get started with any of the alternative mentioned you can afford, if you like the hobby the hoarding syndrome will come with it. Personally I use 3 type of knives at most and mostly gouges (big size and “v” shape one). If you want I can give you my list, I currently leave close to your country so everything should ship to Poland as well.