seeking modules and software inclusions..

Does anyone have any idea how to implement out sourced products with imbedded source codes?
How can I include product lines into my website like the fallowing example:

ie:
http://www.ramones.com/
and http://www.misfits.com/

if you do a test and fallow me youll see what im talking about:

find a product.
they have outsourced their products through a company called cinderblock.com
this is typical now days.

so what if i want to impliment spreadshirt.com?
or perhaps other sites that have custom pages of your own with your products?

at the same time, like the first examples above, you have statements and advisory listings through out the site,
stating that you will be leaving the site, and they have included (in most or some cases) links to "go back".

this is mostly php functionality i believe, but i would love to talk to someone who knows whats going on with this
and just to get a better "general idea" of how this is achieved.

thanks for any and all help. i really appreciate it.
please share, this helps everyone out.

not only that but i support my local economy as much as i can, even if i have to outsource to larger
online companies just to get started.

thanks again,

kasperjames