Your location is going to impact the price, but I think it's reasonable for a man to pay $40 and up for a quality cut. If you're trying to not only look professional for work, but also more attractive to the opposite sex -- you don't want to go to a place like Fantastic Sam's or Supercuts, where you'll likely have your hair hacked up by recent beauty school grads. I'd advocate finding a quality barber shop, they still exist and if you find a nice one, the ambience is pretty cool, too. It's one of the few places in modern times you can go and find only men. Barbers are professional, but if an F-bomb drops while cutting your hair or giving you a shave, no one's "offended".
As for how often you should go, it depends on what look you're going after. Obviously, a nice fade would have to be attended to on a more regular basis. They'll tell you to come back every four-to-six weeks, but that's really not necessary if you're just looking for the occasional clean up and not a high-maintenance style. Barbers/stylists only say that so they can continue to pay the rent.
You might think hair products are a rip-off, and some are, but there's a world of difference between how your hair will feel if you wash it with a quality shampoo versus some Suave crap you picked up in the discount aisle at the supermarket. It's worth the few extra bucks.