TL;DR: Take a taxi; or take a train, arrive early and use the money you saved on a nice meal/nasty bottle of baijiu at the airport.
First of all, a sanity check: a normal metered taxi from central Shanghai to PVG should be on the order of ¥150, or roughly €20. If that's "too expensive", you're really not going to like the prices in Paris! (The same ride there would cost you at least 3x as much.)
But the good news is Wikivoyage seems to be out of date (for another few minutes, anyway), since according to the official Shanghai Metro site (in Chinese) the last train on subway line 2 departs Guanglan Rd (广兰路) at 10:00 PM, arriving around 10:30. Note that Guanglan Rd is on the eastern side of the line, and you'll want to depart People's Square around 9:30 to catch it.
The last maglev leaves Longyang Rd at 9:40, but this won't let you hang around Shanghai any longer, since you'd need to leave People's Sq around 9:20 at the latest to catch this. It's a much comfier and zippier ride though!
Last and least, while all other shuttle buses stop at 9:30 PM, Line 1 from Hongqiao Airport & Hongqiao station keeps running until 11 PM. This is unlikely to make much sense unless you're arriving from western Shanghai though.