9 plus 8 equals ?

I have been on hold with math for Madeline the last couple months.  We finished Saxon Math 2, and I realized she doesn't know the more difficult math and subtraction facts very well.  She knows the concepts and could explain the process of addition and subtraction.  But, the answers are not automatic in her mind.  She has to really think about them or count on her fingers.  This is a problem, because everything from here on demands a mastery of simple addition and subtractions.

I told her we weren't going to move on until she has those facts down pat.  We have been drilling the fact flashcards and completing math fact worksheets.  It has not been fun.  Madeline likes math.  She likes learning new concepts and picks up on them quickly.  This has been drudgery for both of us.  I really feel like we have to get through this.  Looking back, I think that because she does understand the new concepts so quickly I did not spend enough time drilling the facts.  I figured that since she "got it" we'd keep plugging along.  Now I realize you need to master each step along the way, even the ones that you understand.  It needs to be automatic.  

I recently purchased 1st grade and 2nd grade workbooks for her to complete.  It is all review for her, and is pounding those facts in to her head.  Once she finishes the workbooks, we will move on to Saxon Math 3.  

I offered her a deal a couple days ago.  She needs to finish the 2nd grade book by February 19.  For every day she finishes it early she will get a dollar.  If she finishes it 8 days early, she'll get $8.  If she finishes it after the 19th, she owes me a dollar for every day.  Madeline likes to earn and save money.  She just bought a Lego airport set for $90, all of her own money.  So is my deal a smart mommy move or a bad mommy move?  Is it bribery or motivation?