Doctor Who: The Problem of Getting to Know the Eighth Doctor
However, the comics that appeared in Doctor Who Magazine previously held the title of most-likely canon to the extent that Eight's regeneration was originally supposed to happen in their pages. Regardless, once you have McGann's voice in your head the comics are a great avenue to explore. Scott Gray has some really tremendous arcs, and without the budget of the show to hold it back the stories have absolutely fantastic visuals.
Though the Gary Russell Radio Times comics are sadly not collected anywhere (He confirmed with us via Twitter that he has offered them to IDW, who were not interested in republishing them), all the DWM strips were collected in four trade paperbacks by Panini Press. Three of them, The Glorious Dead, Oblivion, and The Flood are still in print and easily available. Most of the Eighth Doctor's comic output can be had for less than $50.
Unfortunately, Panini allowed the first trade, Endgame, to go out of print and has no plans to reprint it. That means the only way to fill this gap in the comics is to either track a copy down on eBay, where they fetch at least $100 if you can find one, or buy old copies of DWM individually. Issues usually don't cost more than $7 on Amazon, but you have to buy more than 40 to get the entire missing strips. There's nothing wrong with jumping in at The Glorious Dead. In fact the writing and art has tightened up considerably by then so the stories are much better, but it's frustrating that the whole set is almost unfillable.
The Books: In the time after the film the Eighth Doctor lived on in a series of more than 70 novels. As is often the case with spin-off models, they are of varying quality, but the ones that are good are absolutely magnificent. John Peel's Dalek stories are some of the best in the series, and Kate Orman turns in several entries like The Year of Intelligent Tigers that are more than worth the read.
The first book in the series, The Eight Doctors by longtime series novelization master Terrance Dicks, is essential reading for all Whovians. It's not very good, honestly, but the reconciliation between the various timelines as Eight seeks to cure his amnesia by observing his past selves makes it a vital tome in the overall mythology.
The books are also the most expensive way to experience the Eighth Doctor. Most of the early books run $20 to $30 used on Amazon, and few are available on Kindle. Those that are suffer from terrible formatting that makes the savings almost pointless. As the series progresses, the price drops off some, but there are enough spikes here and there to insure that you'll drop at least $1,000 collecting them all.
There is so much apocrypha in the world of Doctor Who... so many stories that probably no one has read, seen, or heard them all. With all the celebrating we just did of 50 years worth of the show's history, it might be nice if some of the folks at the BBC started giving some thought to preserving and making these edges of Doctor Who more easily available to a fandom hungry to find out more about their new favorite Doctor. Unless we get our wish of a new web series, it's almost all we've got of Eight.