It seems a bit high to me, sam. On my printer, I could easily print four blocks at a time, possibly all eight. However, the printing time for each block has to be factored in. I didn't time the printing on my machine, but I suspect it takes between 1 - 1.5 hours to print each block. Printing more than one at a time simply adds to the printing time by multiplying that time by the number of blocks (2 blocks, 2 - 3 hours). The plastic cost is fairly minimal. I can get 4# of PETG or PETG-CF for less than $30 and that will print a LOT of blocks. My printer hasn't produced a huge hit on my electric bill - nothing I notice, and I've printed quite a lot of things.
But preparing the blocks for shipping takes time too, so that has to be factored in. I think $10 is reasonable.
My guess is, your neighbor simply wants to make it worth his while to print these things. You might find the cost is similar at a 3D printing shop.
I know I'm not interested in doing this, because I have other things I'd rather spend my time on.
- Jack