I found these toothbrush holders at Toys R Us and I am so happy that I bought them. They are not the cheapest things (about $4.99) but are a total answer to our problem. The kids toothbrushes stay clean, the baby can't reach them, and the kids can use the holder for overnights!
Here's a pic of ours at home:
Go to myflipperusa.com for more information. Besides Toys R Us, the only store that I can see on the site that sells them in MN is The Container Store in Edina.
I noticed you can buy them at Target.com but they are selling for $10.99! Urbanoutfitters.com has them for $8 & Amazon.com ranges from $6.49-$10.99. Wow, I guess in hindsight, $4.99 at Toys R Us wasn't such a bad price.
Flipper meets every guideline for toothbrush care established by the Center for Disease Control (CDC) and the American Dental Association (ADA): "The easiest way to protect your toothbrush is by using a toothbrush cover. Splattering water, contact with skin, and toothbrushes knocking against one another are all circumstances that contribute to the spread of bacteria."