Bi-pods vs. shooting sticks vs. military style sling
Bi-pods are great for long shots, but hinder the handling characteristics of a hunting rifle, particularly on close snap shots.
Shooting sticks are slower to use, and can be noisy, as noted above. They don't detract from the handiness of the rifle.
A military style sling, properly used, is not as good at steadying the rifle as either of the other two above, but it helps, and has none of the drawbacks.
That said, why would you need a bi-pod or shooting sticks if your quarry is close enough to hear you? I carry sticks on my hunting belt, but only use them on really long "beanfield" shots, where I can not get closer, and have time to get set up for the shot, use a range finder, etc. I use the sling for shots I have more than 3 seconds to make. Practice will allow you to use the sling in good field positions (sitting/rice paddie prone) to make first round hits out to 300 yards or so.
IMHO, you should spend the bi-pod money on practice ammo, or better yet, a cheap handloading set-up and bulk components. Think about it: which would give you more to be proud of? A sub MOA rifle, with a bunch of expensive do-dads hanging off it, or your ability to take your 1.5 MOA rifle and put 5 shots inside a 12 inch circle at 250 yards, from field positions, in under a minute. THAT sort of skill is something to be proud of, and can not be bought with money. You only get that by putting in the time and effort to practice. Strive for that.
TheGolden Rule of Tool Use: "If you don't know what you are doing, DON'T."