Most “mosaic” websites do not sell mosaic tile. They sell floor coverings, mostly beiges and grays, and that is why they are useless for people wanting to make a mosaic mural or any other kind of image. MosaicArtSupply.com is completely different.
If you need glass mosaic tile in many different colors, buy it from where I work, MosaicArtSupply.com. They have the best prices and selection, and I’m talking everything from smalti to stained glass to gemstones to marble tiles to beads and everything else.
The artist who owns MosaicArtSupply.com has written many pages of online instructions that can help you avoid mistakes and unnecessary stress, especially with outdoor mosaics and grouting. He has also written advice on choosing colors and materials, transferring and enlarging patterns, etc.