Yes, there are many usb wall chargers on the market.
I can't give you an example of which are good quality, but I can tell you that most of them are"get what you pay for" quality.
Apple makes one that's around $30, last time I checked.
There are others you can get for less than $10.
I don't mean to advertise, but the one I choose is an Energizer brand PS3 controller charger.
It has two mounted type /b/ usb male slots, and two 2.0 female usb slots.
It's not the one I recommend, but it's the one that works for me.
If you're shopping online, I'd suggest amazon.com, or newegg.com.
If you're not shopping online, I'd say look up your local radio shack, or standard electronics store.