Can you recommend high quality cycling-centric films? Can you recommend good sources (for example, publishers, distributors, vendors, etc.) to locate these films?
Old but still worthwhile: Breaking Away.
Hell on Wheels is a German movie portraying Erik Zabel and Rolf Aldag during the Tour de France 2003. It gives quite some insights into cycling on that level (while it ignores doping and we meanwhile know that the participants did quite some doping during that time ...)
Blood Sweat Gears is a documentary on Garmin Cycling Team, a good alternative to watching TdF dvds.
It's no Breaking away, but check out American Flyers too. You've got your Kevin Costner, cycling, iconic scenes, and Russian bogeymen.
The Sufferfest offer motivational/training videos.
Also, Bromley Video in the UK has lots of DVDs, books, videos etc. of all things cycling - grand tours, races, bios, documentaries, dramatisations. Not particularly cheap but the best selection I've seen in a single place, also some of the DVDs are self-produced so I'd imagine are unavailable elsewhere. I think they also have an eBay outlet, you may find some things cheaper on there.
In 2009 director Alex Gibney set out to film The Road Back, a documentary on cyclist Lance Armstrong's comeback year after a four-year retirement from the sport. Three years later, on October 2012, a doping investigation led to his lifetime ban from competition and the stripping of his seven Tour de France titles, and the documentary was shelved. On January 14, 2013, three hours after his appearance on Oprah, Armstrong went back to Gibney to set the record straight about his career.
If you are into mountain biking at all, I highly recommend any/all of the NWD (New World Disorder) series, and also the films The Collective made. NWD is pretty much straight up old school bike Pr0n. Professionals on bikes doing ridiculous things to awesome music. The collectives movies were a bit more artsy, but very close to the same thing; both sets were well done.
Finally I'd also like to recommend Bang Bang, which was a film that sort of revolved around Aaron Chase and the year he broke his back. It's very behind the scenes and gave me a very unique perspective on what some of the riders are actually like and how to some extent "the show must go on".