I am sure you will get a variety of answers, but when I dry hop I actually use nude colored women's pantyhose. You cut them off at the top of the leg. I soak them for a couple of minutes in star san prior to use, wring them out to knock off the excess star san, insert hops, and drop them in. The nude colored hose won't impart any offs or dyes into the beer and are the right mesh size to keep the hops contained through the dry hopping process. Much cheaper than muslin bags and you just toss them when you're done. Dump the hops in the toe and tie the knot near the top of the leg. Plenty of room for expansion of the hops. I don't personally weight mine down, though I know some people do, as I have found the hops will typically float in the hose and I can easily reach in with a sanitized spoon and remove them when the dry hopping schedule has elapsed.