Definitely buy the hardback version of the book. Don't bother with the paperback (you can read that version free, legally, online), just get the hardback now. Considering the thousands of hours it'll take to get a handle on the material, the cost is nothing.
More info on the hardback, and the differences here:
http://magicref.tripod.com/books/bobocoin.htm"Modern Coin Magic" is the public domain edition (which you can get in various places - legally - for free). Dover reprinted this when the copyright lapsed, because apparently Magic inc. didn't renew all their editions correctly. "The New Modern Coin Magic" is the (hardback) revised edition, with 4 new chapters by Bobo and a bibiography, amounting to an extra 150 pages of new material. Also, by buying it, you're apparently supporting the author's estate, i.e. the family of the guy who wrote the actual book. Which you should obviously do, unless you value his work so little you think it's not worth paying for.
On the Ben Salinas DVD set - it's very good, amazingly it has nearly all the material in the book, and it's well presented. Pretty cheap, too, considering it's 4 DVDs.
You can read the public domain edition of the book for free, online at google books, or at "the learned pig project", if you sign up for that (which is a good idea). Or you can pay for the download at lybrary.com, which gets you a searchable pdf for $8 (rather than the annoyance of being online). But don't do that. Make the commitment and get the better edition, with those extra 150 pages. Check out the chapter listing at the URL above - chapters XVII-XX are the 'new' ones. So much more material and revised teaching material. It's an easy decision.
Some of the stuff taught in the hardback that isn't in the free edition:
The Goshman pinch. It's the basis of a load of brilliant routines, e.g. Tenkai pennies, coins across.
Loads of Okito box material
Slydinis coins through table
Sun and moon, c/s coins and other gaffs
I could go on but I've probably annoyed you all enough by now. Buy the bl***y hardback!