Yes, they were available to buy as a Volvo Accessory. I still have a '71 140 accessory pamphlet and the '71 140 rack looks a little different. That looks like the earlier rack that was sold for the Amazons, particularly if the slats on the bottom are wood. By '71, the official 140 rack luggage rack (there was a separate 2 bar rack for skiis) was all metal tubing with metal tubes replacing the wood bits. The top surrounding rail was a one piece black metal tube.
If you want that exact rack, do a Google search using "Volvo Amazon Roof Rack Wanted to Buy". You might get lucky and find a seller. This is the wagon version
Maybe a Volvo accessory rack if Volvo purchased a Thule rack and put a Volvo sticker on it! The mounting pedestals / foot kits and cross bars look exactly like the ones on the Thule Kayak rack that is on the roof of my 142 right now.
That seems like an ambitiously high price for a used rack that was probably purchased 20+ years ago. If you didn't specifically want the highly sought after Amazon style wood rack then a little searching should get you a luggage rack for a lot less than $350 US. Any rack that will fit on the Volvo 740 / 760 / 940 models which still had roof gutters will fit on the 140.
I've hunting for the wagon version for years. I found one in Europe but it was $650 plus shipping (still considering it in my desperation). I haven't come across a sedan version in my search but I'll keep my eyes open. Vintage racks are getting spendy. I guess they're on trend right now.