I've never sent my cards into Beckett, but my LCS had a Beckett rep drop by this weekend to grade cards in person. Since they were visiting in person I got a good deal for a 10-day turnaround (~$10/card+shipping and insurance). But I know if you send it in it's more expensive ($14/card for 10 day turnaround).
I've seen people use PSA also for card grading, and they are about the same price ($15/card for 10 day turnaround). I don't know which one is more respected though. Also, to grade autographed cards will cost a little bit more.
Talking with the LCS owner he recommended not to get modern cards graded if they are not a 9 or higher. An 8.5 won't really bring much value for the amount you will spend to get the cards graded.
Here's the pricing for PSA and Beckett. Hope this helps!
PSA 2012 Services and Fees
BGS Services and Pricing