Can I get more sounds/types of guitars on GarageBand for the iPad?

I have been attempting to record some of my personal songs on GarageBand for the iPad. However, I am very unsatisfied with the lack of smart guitars. Because of the fact that I don't own an electric guitar, I am unable to plug that into my iPad to access the guitar amps on the app. Being limited to the Smart Guitar, is there any way to get more guitars or perhaps edit the sounds of the existing guitars? Thanks a lot.