I'm building a recording studio. I need to record drums. I know people use a mic for every drum and cymbal, but I cant afford mics for an 8-piece drum kit with 6 cymbals. I'm thinking of getting only 2 mics, (because 1 mic won't get everything) but I don't know if it will sound good because with more mics you need to mix all the drums. w0t du iy du? (TRANSLATION: What do I do?) Tell meh!!!
You can call me Crazy.
A well-tuned drum kit played by a skilled drummer can sound great when recorded in stereo.  Mic placement is important and it severely limits your mix options but you can get good results.  A lot of epic hit records were recorded that way. 

We record with the tools we have, not the tools we wish we have.  Mad skills can overcome a lot of gear limitations.
"Your sound is in your hands as much as anything. It's the way you pick, and the way you hold the guitar, more than it is the amp or the guitar you use." -- Stevie Ray Vaughan

"Anybody can play. The note is only 20 percent. The attitude of the motherfucker who plays it is 80 percent." -- Miles Davis

Guthrie on tone: https://www.youtube.com/watch?v=zmohdG9lLqY
It depends what you want it to sound like. The drums on most mixes these days don't sound like a drummer in a room, so unless you specifically want that it will be difficult to mix it any other way.

If I was seriously limited then I would use two overheads, a snare mic and something on the kick so I can trigger it later. If you want it to sound like a modern rock or metal mix then really this is the minimum. Unless the drummer is absolutely fantastic I wouldn't be comfortable just using overheads unless, again, you literally want it to sound like a dude in a room.
Its all about the acoustics of the room you're playing/recording in. The drums for "When The Levee Breaks" by Led Zeppelin was recorded using two mics overhead in a foyer. Its all about the sound you want. Explore the space you have and try the mics in different places before settling. i once recorded drums in a medium sized furnished bedroom using a cheap computer mic behind the kit and it sounded pretty well. Multiple mics are for micromanaging your volume or sound giving you the ability to produce an even mix, so if you're not going that route you need to keep that in mind.