Where can i find them shipped in Italy at a good price?
Their main purpose would be to shorten the key travel (i've OEM profile keycaps), what thickness would you suggest to bottom out as near as possible to the actuation point?
Get thicker hard ones if you want to bottom out near the actuation point without them feeling really mushy. You may have trouble getting the caps onto the switches, though, unless you have some way of holding the stem up while pressing the cap down.
Maybe you can cut them and put them around the round part of the cap once they are mounted, but that may be really hard due to the limited space and angles.
Any online store should be fine to buy them from, since the value should be lower than the customs limit.
If you are willing to open up the switches, I recommend the trampoline mod (
http://geekhack.org/index.php?topic=50632.0 ) instead. Can then set the amount of travel reduction and how it feels when bottoming out by changing materials and length of insert, it doesn't depend on the type of caps you use and you can fit the caps easily.