Anaglyph 3D is a stereoscopic 3D effect achieved by means of encoding each eye's image using filters of different (usually chromatically opposite) colors, typically red and cyan. Anaglyph 3D images contain two differently filtered color images, one for each eye. When viewed through the "color coded" "anaglyph glasses", each of the two images reaches one eye, revealing an integrated stereoscopic image. The visual cortex of the brain fuses this into perceptive stereopsis.
There are a few companies that offer this service, but it is not common. It generally requires special software and hardware to do.
There are many services that can convert side by side 3D to anaglyph, and they vary in terms of quality and price. However, it is important to choose a service that is reputable and offers a good value for money. In general, the higher the quality of the service, the higher the price.