Here's an easy solution for cleaning pens. It's especially good for cleaning acrylic inks from nibs:
3-1/4 cups water
1 cup ammonia
1/4 cup rubbing alcohol
1 tsp. dish washing liquid
I use an ultrasonic cleaner to clean broad nibs, so I go through quite a bit. It's easy to double or triple the recipe and store it under the drawing board in a washed out milk jug.
For pointed pen nibs, there is another 'homemade' pen cleaner I like to make:
This one still looks fairly presentable because I only just cut the potato in half and wrote a few lines so that I could snap a photo of this tip. After a day of use, it looks pretty nasty. I can use the same potato for two or three days. Red potatoes have very thin skin so once the flat cut side gets mushy, you can place it flat side down on a saucer and keep using the potato for a few more days. Keep an eye on it thought, it might go moldy.
It's great to have a potato at the ready in case the phone rings or someone comes to the door--just stab the tip into the potato and off you go!