Yes, you can use E6000, but that can get expensive if it is a bigger mosaic.
The GEII silicone also comes in squeeze tubes at any home improvement or hardware stores. It comes in clear, and is about $5.00 for a tube that will do a few projects.
If you're doing a project for outside there are other adhesive options, too.
Please, post pictures of any mosaics. It would be nice to see others work.