I'm assuming you want blanks for a euro style knife, not serrated or any other type?
You can buy lengths of HSS that's 50mm x 4mm about 500mm long from certain places like Woodford tooling for about £25, once you've got the steel you'll want to drill some holes in it (5mm holes if I remember right) and HSS is a very hard material to drill so you will need a solid carbide drill that will also set you back about £10 too. The distance between the holes need to be fairly precise too otherwise the cutter won't fit so you'll need to take your time to mark them out. That's probably the cheapest way to do it but it is time-consuming to save about £25 instead of buying the blanks proper.
You hear the horror stories of people having knives thrown through them (I know a couple of people including my old boss who had it happen, Luckily his tape measure took the knife rather than his gut ) but I would say every time you have this sort of thing happen it is always down to operator error rather than anything else. Using worn out old style unpinned blocks, cutters not clamped properly, not enough meat of the cutter in the block, no guards etc is going to be a recipe for disaster whilst if you have your head screwed on properly and do everything in a safe manner there is little to go wrong especially with the euro style blocks, you'd have to be very clever to lose a knife with a euro block as it's centrifugally locked when rotating, pinned in place and the locking block is screwed tight.
Interesting video on grinding Euro knifes if you haven't seen it already:
That's the answer I was looking for. I've seen the video before, it's very interesting and informative. I ve just made some tool rests fir grinding my own cutters see picture which seem to work well. Will investigate further.