In general I don't like the idea of CGC grading modern books as I consider them common in high grade. There are lots of people building high grade CGC modern sets who would disagree with me.
As a general rule it doesn't make sense to pay for grading on a book that will be worth less than the cost of grading. The newer the book the higher the grade needed to justify the cost.
Check ebay, clink, heritage, dealer sites and GPA (a web service that tracks sales of CGC graded comics-google gpa comics) to establish what a book sells for at a certain grade.
awesome advice! i do get my rarer modern variants and con exclusives graded, but it will be some time before i even consider starting a modern set - although they are impressive. to me it's too high of a financial commitment without a possibility of getting your return back if something happens... say your wife gets pregnant!
I follow thehumantorch's basic idea behind it, though all of my slabs are Modern. If you can't make your money back on it, don't slab it. IMO, 90% of Moderns (minus keys obviously) are only worth something in 9.6-9.8, wiith 9.8's being the only real money-makers.
I personally say if it's a sure-fire 9.8 that's not too overpopulated on the census, sub it.