I think we can all agree that nerf darts are way to expensive; for me it is the limiting factor for nerf gun fights, because my modded guns pretty much shoot the darts to china, so of course I never see them again. there are some decently priced dart packs, but it is hard to tell them from the cheapo fake darts.
Some dart buying tips: do not buy darts on ebay, there are so many fakes that look very realistic; nerf only sells dart refill packs in multiples of 6 (12, 18, 30, etc.), or 75 dart packs. So if you see packs of 50 or 200 they are probably fakes with hard plastic tips. Don't buy them. Amazon.com has packs of 75 real nerf darts for 10 dollars. that's the best I've found. hopefully nerf will lower prices someday, but I doubt that will ever happen.