Need Help!- machining various plastics including bioplastic

[anchange]

I'm designing a little (ebay / etsy) product that is going to be injection molded and then CNC routered afterwards. Ideally I want to use bioplastic PLA. I have a sample coming that I'm going to play with, but the three options are PLA, PS, and PP.
This is what the finished part will look like –
http://dl.dropbox.com/u/455762/DSCN0677.JPG
The operation that I’m trying to do is a router cut all the way through a thin wall of plastic.
I would like to know more about the machinability of each type of plastic. Sense the PLA is a soft plastic will it machine nicely in this circumstance? How about the PS being a harder more brittle plastic? Do I need to use special cutters for this or just standard HSS endmills? Any advice is very much appreciated.
Thank you for your time!
Brad

[xerophiles]

I would not get hung up on "green", almost all termoplastic choices are recyclable. The correct questions to ask are based on end-use and the environmental conditions that the product be subjected to. Whoever does your injection molding (a large expense for and ebay project) should be able to direct you to a range of materials suited for your application.