Also in Australia. Yes M3 and M4 bolts easier to find. I just used M4 and when required drilled out the M3.5 holes. Or (in the case of the Z axis nut trap) redesigned the part for M4.
Yes the M8 bolts were hard to find in the lengths listed, most I couldn’t find in Bunnings (or the now closing down Masters). So I just ended up ordering the complete set of bolts in length and qauntity on line from an Australia Distributor. They arrived in a reasonable time frame.
Important to note: The bolts need to be the length listed. Not 5mm longer or short. The exact length. the tollerances and clearances are very tight.
As for the M8 (in the Model F) tapping. Yes. they did. but as far as I can tell with my build it didnt degrade the placement and tension/alignment of the bearings. All mine worked perfectly, and the ZXY come out perfectly square (to the limits of my obeservation and testing).
Actually the bearings were the easiest to come by. I found them both at a bearing supply shop, and they also pointed me to the fact that any skateboard shop carries the same size bearing usually in packs of 8 (to replace all the bearings on a board).