Brownells has them for around $30 each.
Understand that using ammo to check headspace doesn't work...well almost. If you can chamber a live round, the you have figured out that the headspace is not too short. You have NOT figured out if the headspace is too long...and this is critical.
Now if you understand the principles of measurement and the specs of an AK chamber, and add shims to the back of your live rounds, and can measure things to the sub 1/1000 of an inch, then you might be able to do a fair at best job at checking headspace with ammo, shims, and calipers.
Or, for a measly $30, you can check it correctly and save the money and hassle of potentially blowing your hands, face, etc. off.
No flame here, believe me we all hate needing a special tool that we don't have for a step that may be totally not needed...but look at the risk involved...
Good luck!