Can anyone recommend a good website or hobby shop that may have parts/pieces?

Ok, thanks for the info.

I have a TGV set I got for Christmas about 25 years ago, and have had on the shelf for years, it's only been out of the box a handful of times. I went over to my parents yesterday to grab the TGV to set it up and play with my 3 year old boy who loves trains, but I have somehow misplaced the coupler/trucks for the passenger cars. Anyone have any idea on where I can find replacement couplers at? Any info would be greatly appreciated.