I use those really thin cotton face washer type things they have in packs of ten in the shops for babies. I reckon I have about 20-30 of them, but wash reasonably often because I use cloth nappies.

I have them in a stack, dry on my change table. I also have a pump pack (resued an old hand wash bottle) of water on the table. I just squirt a few squirts onto the wipe and use as normal. You can also put a bit of lavender or camomile tea as a weak solution into the pump pack if you like that sort of thing.

I wouldn't wash in with my other clothes - a bit too dirty for my liking. But it would take you forever to get a load's worth to put on a special load? Maybe wash with your towels?