Two used Oktava MK-012 mics. Definitely. No question. You should be able to get them for $200 for the pair on eBay if you work at it, $250 at most. It's worth scraping up the extra $50.
Don't get me wrong, I love my Naiants, but they are omni mics, which makes them not nearly as good a choice for overheads, IMHO. I much prefer having my drum kit actually having some stereo spread coming from the overheads instead of just sounding like everything is panned almost dead center. It's a lot easier to get that with cardioid mics than omnis. If you're doing the Recorderman technique instead of an overhead X-Y, using cardioid mics is less critical, but even still, cardioids are highly recommended to reduce bleed and room reflections.
With omnis, you have to do either a spaced pair or a Jecklin Disk to get anything remotely approaching stereo. I've never liked the sound of widely spaced stereo miking, and a good Jecklin Disk will run you over your budget by itself. As a result, with cardioid mics, you're in control of the mics; with omni mics, the mics are in control of you.
Naiants would be my instant first recommendation for guitar or for low-cost recording of piano. I've also used them on flute and cello in a live sound reinforcement capacity with great success. But they definitely wouldn't be my first choice for overhead mics.
