I have an Infinity Pro and like it; but I am a bit paranoid about getting replacement batteries for it.
The postage cost will double the price of three sets of them.
It is a bit like I remember when I smoked sitting at home on a Sunday evening and wondering if I should go and get a pack of smokes before the store closed.
Inevitably I went, but rarely opened the pack before Monday afternoon.
I ordered a Twist last week to help solve this problem.
I would email them and ask about shipping costs for some extra batteries, hopefully they can arrange something more affordable.