Okay, so most lint has small amounts of thread from clothes, which we can extract. With it, we can further make felt, paper, yarn, clay, or fire starters.
Let's go with yarn
So yarn goes for about $5 a skein of 200 feet. Lint is say, about 90% actual clothes, after some math and research, the average amount of lint produced in a day is 1.9mg. cotton (assuming that that's all that is being worn) is 770 kg per cubic meter.(here I converted to yds but I forgot to keep track of the original decimal I got for meters soz) That equals ≈.000000002698526323272091017 of a cubic meter of lint each day. Dividing by 200 (for the avg length of a skein of medium yarn) you get 741145262417 days of belly lint needed to make one skein of yarn, or about 27073799.5 lifetimes. Moving on, that means that a days worth of belly lint is worth $.0000000000067463158 or .00000000067463158¢.
-Your friendly neighborhood Slytherin Sunagakure shinobi