Chassis and Ohio Enthusiast laid out the history of the boxster well and what to avoid. Basically cross anything pre 2009 off your list and start from there. The 4cyl 718s are widely disliked by "Porsche Purists" because the little 4 cylinder sounds like a Subaru, and Porsche engines are supposed to be high revving flat 6s - but if your wife likes low end torque as opposed to ringing an engine out at high RPM, she might prefer the 718. The interior is vastly superior to the previous gen cars as well. Something like this would be a nice option (assuming it's been taken care of):
https://www.cargurus.com/Cars/invent...NWIDE_SHIPPING
https://vinanalytics.com/car/WP0CA2A89HS220621/
Some of the online car for sales sites filter boxsters by generation (987, 981, 982/718) so you may be getting cut off due to that. I personally like autotempest to search because it consolidates a number of sources into one output:
https://www.autotempest.com/results?...le&title=clean
From first pass, it looks like early 981s are your sweetspot (2013/2014) they're pretty robust and if you can find one that has decent maintenance history, you should be pretty low risk. You'll have to click through the for sale ads, because a lot of PDK (automatic) cars are listed as manuals. It's really frustrating.
Porsche Options are all over the place, so pay attention to how each one is built. Most options are individually chosen (vs packages on the BMW side), so you can find some very weird builds out there. Vin Analytics is awesome for getting build sheets:
https://vinanalytics.com/
just type in the VIN number and it will spit out the build. It even has a widget that you can install into chrome that allows you to click directly from a for sale ad and pull up the vin report.