I built the boat a few years back and timber prices have changed a lot in the past few years - so I don't know.
I got the balsa in the form of rough sawn flitches about 4"x5" by either 8ft or 10ft long. Then resawed and cusp and coved to make strips finished 7mm x 24mm. (How simple sawing makes imperial size timber goes metric is a bit of an Australian miracle - a lot of us use both systems!).
The short lengths were not a problem with quick joining using cyanoacrylate glue. In fact I just made continuous strips and docked them to close to the right length for each strip as needed. Balsa wastage would have been less than 5% once the strips were milled.
Basically it was the raw material that is sliced to make end grain balsa. So less processing probably means it will be cheaper. Not REAL cheap, but cheaper.
I got my balsa from "Australian Balsa". Elsewhere in the world the only name I know of is Baltek
One thing to be aware of if you manage to find a supply - the sap wood is pretty spongey so is best avoided - when you go to sand it compresses rather than abrades. In the lot I used it had a slight pink hue so was easy enough to avoid.
But the building was pretty trivial in terms of effort - a few tricks to learn about not denting the balsa as I went but that was it. One of the most fun boatbuilding projects I have undertaken.
Note that it was not really my idea, but a whole bunch of people as mentioned in the first paragraph of the webpage, I was just lucky enough to stumble on the idea of using it for a canoe as cute as the Rushton "Wee Lassie".