Yeah, you can buy it off Amazon, but I'm wondering how much will actually be needed to run a country's electricity infrastructure. (I'm also assuming that the reaction isn't anywhere close to 100% efficient, as far as using up all of the fuel available, whether it's boron or lithium. Reclaiming unspent lithium would be a bitch, particularly since it'd probably be splattered around as a light powder, pyrophoric powder or coating that could burst into flame upon contact with air.) And remember, unlike with batteries or other chemical transformations, once this lithium's been used, we're not getting it back.
Then there's the storage and processing. Lithium rapidly reacts with oxygen, and even more rapidly reacts with water, including vapor in the air. It's pretty toxic, too. It presents a storage hazard and a health hazard that boron does not. With the boron path, I could foresee reactors that could be plonked down pretty much anywhere and run by a few technicians, mostly just needing only someone to shovel pellets into the hopper and occasionally clear out the reactor chamber.
Then, there's one thing you're missing -- if they can get it working with boron -- great! If they can't, quite -- well, it should be trivial to rework the chamber design and cook up some new pellets using lithium. In this design, the chamber seems to be mostly just for containment and capture of the alpha radiation, and feeding in the pellets. I can't imagine that they'd need to rework the most expensive bit -- the laser -- significantly, so it could be, at worst, a few months of time and maybe a few tens of thousands of dollars to get it changed over to try the easier path. So they lose essentially nothing by trying the hard way first, then the easier way if necessary.