Sorry for the delay in reply... been busy!
OK... $250 is a good start if you aren't including the cost of the mic. The mic you chose is a good option for overall recording... its good for a general recording. However, you stated you may want to do some acoustical work (acoustic guitars?). You will probably want to go with a smaller diaphragm mic for the acoustics. I've never heard the perception series, so I can't say for sure, but in a lot of cases, large diaphragm mics don't recreate acoustic guitars well enough by themselves. It's a great mic to start off with, though you may want to look around for a smaller diaphragm mic later on.
You also may want to consider this:
Buy MXL MXL 990/993 Studio Package online at Musician's Friend
MXL is an "off-shoot" of Marshall and AKG. Same internals, different price. I have a few of MXL's mics myself and I enjoy using them. This would kill two birds with one stone.
My favorite thing to do with acoustic guitars is 3-4 microphones depending on the room. Depending on the room, and mics available, my most used setup would be to have a stereo pair (or a single mic in figure 8 polar pattern) set up in the room for room sounds (reverb, echoes, fret reverb, and other room artifacts), a small-diaphragm condenser mic aimed at the fret board (for fret noises and fingering) about a foot away and depending on the guitar, a large or small mic aimed at the body 3-4 feet away. Beautiful. Do be careful for phase issues... they can make or break an acoustic guitar recording. Another favorite is a single small-diaphragm mic. Gorgeous.
Bass cab's. Unless you REALLY REALLY need to, don't do mic them. Bass cabinets tend to be very hard to re-create and are usually more of a pain to get a good sound. You're best bet is to go direct and adding proper EQ and compression to it during mixing. You also need to be careful because you may very well damage a microphone when recording a cabinet. Long story short, try direct first (using whatever pedals or what not as well if you do) and go from there. With such a basic setup and basic equipment, recording a cab is going to more painful than worth it. You'll get a very thin sound.
Electric guitars. Can be difficult to get the right sound/tone. First rule: Stay away from the EQ!!! If you can't get a good sound with just the microphone, then you got problems. It can sometimes take a good engineer 1-2 hour just to get the right position on an amp because its that much different. Also, do not put more than one microphone on the amp or record anything else in the room at the same time or else you'll run in to phase issues and sounds will cancel out or double (both are a big no-no). You will really have to play with it. You really don't want to aim it directly at the dustcap of the speaker. Start off 2-3 feet away at an angle and go from there. Just keep moving the mic until you get the sound you want. Remember... don't touch that EQ!! My favorite mic for electric guitars: SM-57. The mic is just amazing. Go for it.
As for an interface, here are some options for you. The benefit of an M-audio is that you can use Pro-Tools M-Powered if you happen to get it.
Fast Track Pro:
Buy M-Audio Fast Track Pro Mobile USB Audio/MIDI Interface at Musician's Friend
Edirol UA-25:
Buy Edirol UA-25 USB Bus Powered Stereo Audio Interface at Musician's Friend
Both are great options, though I would shoot for the M-audio for several reasons:
Excellent support for drivers, etc etc.
ProTools capable
Lots of I/O
You are well on your way.
Acoustic bass: Large diaphragm mic. These are difficult to mic. You want to aim them somewhere between where the strings are plucked and the vents in the wood on either side of the string a few feet away. Get some blankets and scatter them around the bass to eliminate some boom. Also, turn on the low-cut of your mic to get rid of the boomy sound you'll hear. You could also put another mic to use high up on the frets if you like the sound of it... its a cool effect.
Putting a mic on a cabinet or an instrument is an artform in and of itself. Keep playing with it until you get a good sound. Like I said before, if you have the right mic and the right technique, you'll never have to touch an EQ.
