People are probably going to slay me for this but hey. When i first started buying mics i bought a pair of behringer B1s and tbh they do the job really well, theyre not a microphone that particularly makes anything suddenly begin to sparkle but on acoustic guitar etc theyre pretty go with the right mic technique. The other option is the C3 which is a cheaper version but does give you the option of switchable polar patterns, when using 2 mics you then have quite a range of mic techniques. Or if you can splash the cash then maybe the B2 which is the multi pattern version of the B1. The only other option i can think of, but this would only be a single mic is the Rode NT1AAt the end of the day you need a good chain throughout so if you only need the one mic then maybe a C3 and a preamp like an Art, or again the Behringer version of it may give you some nice results.
Mics:
Behringer C3
Behringer B1
NT1A
Mic Pre:
Behringer preamp
Samson preamp