Hi Empire, great to have you here.
I'll provide my 2 cents, though with the craziness in the market these days, I may be off by factor ot 5 quite easily.
- Should I be looking for just a collet or would I have a better chance looking for a complete bayonet?
Looking for a complete bayo is probably your best bet. Sometimes loose bayo collars are found, but they are few and far between and for a straight eared Russian SKS45 collar from '49 to early '52 you'll pay dearly because 99 chances out of 100 the seller knows he hit gold.
- How rare are these collets on their own and how much should I expect to spend?
Again, '49 to early '52 was the production dates for these so they are not necessarily 'rare', but they are not nearly as common as the slanted slot collars used from mid '52 through '58. I'd guess you're going to pay $50-$75 for a generic bayo set if the seller doesn't know what he has & you can figure out it's the one you need from photos off eBay or Gunbroker. If the seller knows what he has, the collar alone might run you $100 by itself and a complete bayo may go $150 to $200.
- Is there any work-around to stop the droop of the incorrect late collet?
You could always swapout the bayo mount to one that would fit a slanted slot collar, but that would irreparably modify the gun. I've heard of guys tying the bayo shut with light string/dental floss to keep the droop from happening but it always gave me the mental picture of the gun having a toothache. You may be able to insert a shim between the bayo lug ear and the collar slot, though that might be more trouble than it's worth.
Alternatively, you could remove the bayo and cleaning rod completely if it bothers you while shooting. Not ideal at all, but w/o the correct part the droop just happens.