I wouldn't buy them online.
I love going to the bookstore and looking for new volumes, I love having the book in my hand, feeling the pages, looking at the covers, reading it anywhere on the go without having to pay for a Nook or iPad, and not having to look at an eye-killing computer monitor for hours at a time if I want to read a marathon.
I get more out of the story by reading it in the collected volumes, and best of all, I LOVE having the volumes sitting on my shelf.
I just recently cleared a big enough space to have all 53 american volumes sitting side-by-side. It is wonderful. Everytime I walk into my room I see it sitting there and get the biggest damn smile on my face. Digital versions could never replicate that.
Plus, the fact of the matter is, seeing the volumes on the bookshelf makes me a lot more likely to reread them. It's a reminder that I actually own the series. I'm a lot more likely to read the comics and manga sitting on my bookshelf and watch the DVDs sitting on my shelves, the ones I pass and notice every day, than I am to read the comics I have on my computer or filed away in longboxes or the TV shows I have saved to my computer. Because I forget my digital copies exist–I don't have the constant reminder.
For example, I have Cowboy Bebop on DVD, and rewatch episodes fairly often. I have Samurai Champloo saved to my computer (was given to me by a friend), and have only watched it once. I forgot I even had it on my computer for years.
No way. I hope print media never dies out, trees be damned.