I bought an air pump from Walmart for an aquarium and use it as a sonic cleaner. (The cheaper the better. You want it to vibrate as much as possible.)
I just taped a small container on top to keep it from vibrating off and fill it with my favorite cleaning solution (I use hot water) and let it run for about 15 minutes. Then I repeat with clean water twice, one hot the last cold).
If I'm changing flavors I'll add a bit of Baking Soda to the first wash to pull the old flavor out, then do the 2X wash with clean water.