Prefer glass.

First, be aware plastic is a petrochemical product. As you said, plastic is everywhere in use, and It amazes me how subtle manufacturers are replacing glass with plastic. We know their reasoning is not so much safety (breakage) as economics issues.

http://www.earthresource.org/campaigns/capp/capp-health.html
Excerpt: Male Reproductive Abnormalities/Infertility
Studies on phthalates as reproductive toxins in humans are few in number, correlational (since you can't manipulate human exposure to a supposed toxin) and very recent. The large number of phthalate compounds & sources of human exposure make absolute conclusions difficult. Nevertheless, the U.S. National Toxicology Program's Center for the Evaluation of Risks to Human Reproduction Expert Panel concluded in 2000 that DEHP has the potential to produce adverse reproductive effects in humans and expressed special concern about exposure in pregnant and breast-feeding women.(11) Scientists are asking what role phthalates are playing in the decline in human sperm production over the last half century.

//www.curezone.org/forums/fm.asp?i=761920#i

http://www.mindfully.org/Plastic/Plasticizers/Out-Of-Diet-PG5nov03.htm
The amount of migration and corresponding toxicological effects are highly disputed topics, even within the FDA, which has commonly acquiesced to industry in its regulation of technologies that are used in the production of our foods — plastics, pesticides, growth hormones, irradiation, and microwave. This is clear from the mass of expert and citizen testimony against such technologies that regulatory agencies bend over backwards and jump through flaming hoops to please their corporate clients, as they are called.

Perry53211,
Would you be able to find and replace the plastic containers for glass? Have you checked cooking.com or would this be feasible for you since you're in Thailand? Below is a link to a yogurt maker from cooking.com that uses glass jars.
http://www.cooking.com/products/shprodde.asp?SKU=221017