Total spent by the proprietor of this blawg to rid it of typos and grammatical errors: $195. To get your piece of the pie, look here.
Now for the update: Lately, as my eagle-eyed copyeditors have begun to discover even my most minor errors, I've had to add another book to my library--Merriam-Webster's Concise Dictionary of English Usage. (Note to Will Baude: Like you, I also own the OED, but I find it far too cumbersome to consult on a regular basis.)
Why another book? There's a secret about English majors: we really don't know much about grammar. Grammar's for people planning to teach grade school. In earning my English degree, I habitually turned my nose up at grammar; then I kicked it in the shins by choosing to focus my studies on "creative writing." (Please don't snicker. I now have a law degree and can whip your ass.)
Finally, I want to welcome to my group of copyeditors my 14-year-old daughter, who recently spotted a problem with a serial comma. She demanded payment even though I don't pay for punctuation errors. Believe me, it's like her to demand payment. I finally gave in to her argument about the "Oxford comma" and added $10 to her allowance.