#1
Need a mic that will be used to record guitar, will mic the amp. Will hardly record vocals and I have a cajon that will be used a bit. Whats a good USB mic for ~$150?

Or if there is a package that has audio interface and mic for about $200 that'd be good too.
#2
Shure SM57. They make a USB adapter for them now, it comes in a package. Pretty much the industry standard for mic'ing a guitar amp, from my experience anyways.
My Guitars
Squire Affinity Strat
Ibanez RG 350 DX
Fender Stratocaster MIM
Ibanez AEG20E
Tradition Guitars S2000F Pro