The nasal irrigation that my doctor recommended to me is isotonic saline with a baby aspirator (the big sucker deal for noses and ears). If you have a big syringe, that would work fine, too. You want volume without pressure, you're not hosing your sinuses down, you are washing them. And blow gently while irrigating, if you mat down all the nose hairs you could make yourself more susceptible to getting a cold.
You can mix your own solution for cheap. An isotonic saline solution is just 1 tsp baking soda + 1 tsp salt + 16 ounces of water. That's it, nothing fancy.
Some people think hypertonic saline is better, but in my estimation it depends on where you live. A hypertonic saline solution would increase the salt to 2 tsp and will tend to work better to draw moisture. But in Denver the air is dry enough that isotonic solutions work plenty fine without giving me nose bleeds. If you are doing a nasal irrigation only during the time of being sick, then hypertonic will work better, I just happen to irrigate regularly because of allergies and stuff.