Maybe asked already by someone, but I wonder is there some method to 'farm' redstone without using mob farm/ic crops/bees?
You could mine at the level for GregTech redstone ores, or search for Magic Bees hives which usually contain clumps of vanilla redstone around them. Apart from that, it's either go tech up and build a powered spawner or become a Witch Hunter at night for the chance they'll drop some redstone as one of their loot drops.
As others have said, there's always the Nether if you don't care about being shot at by Ghasts and fending off other hostile mobs in the Nether.
Cheers ...
BrickVoid