Need pulley for rear derailleur - Shimano 105 road bike.
More less just the cage i need to replace, as partly broken.
Where can i buy parts such as this , odds and ends. thanks

One source: Bicycle Derailleurs and Parts - AEBike.com

Or you could peruse some of these pages: https://www.google.com/webhp?sourcei...ockey%20wheels

Being in Canada sucks in that regard. Stuff is further apart, UPS shipping really sucks, though USPS is not so bad.
AEbike is in Kalamazoo and may have some familiarity with Canadian shipping mores.

For bits like that the LBS is impossible to beat. Most shops that have been around a while have a bin of crashed and broken components they pull parts from all the time. Generally you get parts for pocket change. There's a shop that I do this in for winter projects. They've been around forever, and have fils cabinets full of derailers, brakes, hubs, and everything else. I've exhausted most of the rarities, but if I need something they probably have something serviceable. The shop I work for has a shelving unit in the back room with a similar arrangement.

Or order from your lounge chair. Amazon Dura Ace Pulley, select the "single" pulley, then the drop down for the 5700. Sold as a pair. $10.30 delivered. https://www.amazon.com/Shimano-RD-670...r+guide+pulley

oh i made a mistake, its not the pulley wheel i need. its the Cage that I need, sorry got my terms mixed up.
so ya i need a new cage

If the cage is bad just buy a new derailleur. Roger

If it's the back plate that's damaged, you might be lucky, but if it's the front - although it can be changed, nobody's gonna do that for you.

And straightening bent cage plates successfully is much harder than it seems; most experienced folks will decline to attempt it.

Well backplate cage is damaged, cracked and i can move it apart. even though i found i probably been still doing 100's of miles this way. i decided to order a whole new derailleur, better safe then sorry