SM 57 FOR CLOSE MICING GUITAR CABS.
it's been used on a million recordings, a lot of classic recordings, timeless recordings....
and a few new ones.
LOL
a BUDGET mic that you would use on a guitar cab, most times will NOT work for a room mic.
a large condenser would probably fill the bill for that,
but a BUDGET mic is just not going to sound that good for a good ROOM mic.
in other words,
you will make a great compromise on your room mics,
if you don't put some budget into it.
otherwise,
just get one of these:
and move on until you can save up enough money to get something really worth while.
personally,
i have moved away from using mics for most of my electric guitar recording.
i use a Palmer PDI-09.
also suggested, Radial JDX, Aiken gold brick