If you want Flite Test foamboard so you can make anything with no changes to the plans then you need to go to Steve Webb ModeLS or similar, they sell through Servoshop- https://www.servoshop.co.uk/index.php?pid=FT4000
You are going to have to suck up the postage costs.
Any foamboard you buy elsewhere will be the heavy EU board, you can use it but it’s 40% heavier. You can buy speedbuild kits if you need them and power packs. Model Shop Leeds do their own version of the Graupner power packs for much less money.