Just another word of caution about Oktavas. A friend of mine bought two mk319's from banjo center and they are VERY different sounding. One has significantly more top end than the other, but both are pretty dark sounding. We did some comparisons with my 4033 and MTG UMT800 on acoustic guitar and they didn't hold up too bad....definitely less detailed and not as tight in the low end, but I think they might be nice for bright/harsh sources, like overheads in a small room. So if you go the Oktava route, you might want to audition as many as you can and pick the one that sounds best to you.

Everyone will have an opinion including me.

I would consider buying a pair of large diaphragm condensers (Apex, Marshall or any of the other decent Chinese mics on the market these days). You can use them on anything really and having a stereo miking option opens up a whole 'nuther world of miking possibilities for you.

Still, there's nothing wrong with the approach you suggested initially. You can do a lot of damage with an SM57 and a good mic pre I've gotten great kick drum and vocal tracks with that SM57. It's a great all-purpose microphone which explains why every studio on the face of the earth has at least a few of them stashed away.