Hi,
I found the part number (68170-89114 - WEATHERSTRIP ASSY, BACK DOOR GLASS, INNER) and on the parts diagram it's in the "Back Door Lock & Hinge" sub-diagram.
Unfortunately, it's discontinued but perhaps you can search around knowing the number and name of the part.
I've been using a combination of partsouq.com as it has interactive parts diagrams you can hover over, plus toyotapartsdeal.com to actually order the parts since they are in the USA and more often than not have parts in stock that partsouq.com says are not available.
Actually, I stand corrected. If you are willing to pay for it, looks like there is a source for the part on Amazon, but it does have a long lead time:
Toyota Genuine 68170-89114 Door Glass Weatherstrip Assembly