The region lock is definitely in place. I doubt ttmode would actually ship, or if they did then they'd get caught out before long.
About the prices - VAT, regional RRP and the website's coding may come into play here. In the UK, tenergy is £45 from the official supplier, which is roughly $64. But that includes VAT, which you won't have to pay if you're outside the EU. So if you could get someone to send tenergy from the EU to the USA you could knock off another 20%, bringing it down to $51. Which might explain where the $50 figure is coming from.