A straight isn't too high maintenance, but obviously it's the only kind of razor that needs any form of maintenance at all. Straights are expensive to begin with, after that there comes a certain point where the total amount spent on cartridges will be higher than the amount spent on the straight razor. You do need to put oil on the razor, but I've always used sunflower oil without any problems. You will also need to hone and sometimes sharpen your razor. The stones will cost you, but the biggest problem is with learning proper sharpening technique.
But err... are you planning on shaving your armpits with a straight? Do you think that's a good idea? Legs okay, but armpits... I dunno!