Thank you a lot for researching this!
So, a 60W converter will definitely work for the one that I have - the rechargeable one, since recharging takes so little power.
Not so sure about the non-rechargeable one though - the data about how much wattage different appliances use is pretty varied. I guess, if I decide to order one which plugs into wall, I'll figure it out when I get it.
Thanks again for the answer!