I would like to buy my first chastity cage and I need help!

First of all I would like to find something that doesn't cost much, possibly under 50 euros (I live in Europe). Also, in your opinion, what is the most comfortable material, especially for wearing it for days and weeks? I would like to buy a small size (since my dick when soft is less than 4 cm long), but I don't know if the small size or the nub type is better. I would also like not to have to use straps, to be as discreet as possible. Do you have any products you'd recommend? Maybe a good one from Amazon so I can have it delivered to a locker. Thank u in advance!