I pumped for 18 months for my youngest son, who was born with a cleft palate and could not nurse. The key things with pumping are to get a really good hospital grade pump (I rented a Medela Lactina, and I've heard good reports on the Medela Symphony) and to pump often. You need to pump at least as often as your baby would feed -- definitely no less and preferably more as a pump just doesn't stimulate your body as a baby would. Good nutrition and plenty of fluids are important. Supplements like fenugreek can help some women, but nothing can substitute for a good pump and a regular schedule. After several months your supply should be well regulated, and you could start using a less powerful pump (the Medela Pump in Style is fairly good).
I have to admit that pumping was hard work. I gave it up when Nick was 18 months and used formula. I applaud your decision to do it, and I hope it works out for you. If it doesn't, you can be proud that you've given your son the best possible nutritional start in life.
If you do end up using formula, get a version with DHA. In every other industrialised country but the US, DHA is a required ingredient due to its benefits for brain development. Apart from that, all formulas are pretty much equal, as their nutritional content is mandated by the FDA, so it comes down to individual preference. Similac made my son's poop smell disgusting :-) but Enfamil Lipil was okay.