My favorite overheads are AKG C1000s. I got a pair of them off craigslist for $250 and another used one at a music store for $100. Small diaphragm condensers are more of the norm for typical overhead techniques, but I would maybe suggest trying some of those since you have a kick and snare mic already. The main benefit of the recorderman technique is getting a good total kit sound from two mics, especially kick and snare, but the cymbals tend to show up pretty weakly in this setup. I find it works well for a live performance where the cymbals will really fill up the space acoustically, but the recorded takes won't be as stellar. Since you have a kick and snare mic, I'd suggest trying some spaced pair or XY techniques for your overheads instead.
Another investment that you should look into is getting some nice studio boom stands. Sometimes the ability to place a mic a foot or two higher can have a huge impact on the sound, maybe bigger than the difference of what mic you use.
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