Another first-hand experience,
When I went to university (and broke), one Saturday I went into a Christian bookstore and saw a $40 book that I really wanted ("Calvin's Institutes"). I decided I couldn't afford it, but on my way out of the store, I saw a sign that the next weekend the store was having their 22nd Anniversary and EVERYTHING was going to be 22% off. I decided to come back the next Saturday and buy the book for about $30.
When I got back to residence, I had a strong sense that I shouldn't buy the book. I didn't know why - other than the fact I was broke - so I decided I should pray about it and see God would let me know one way or the other if I should buy the book.
I prayed about it before bed Monday night, Tuesday night, Wednesday night, and by the time I finished praying Wednesday night, I "knew" in my heart that I shouldn't buy the book. And I decided I wouldn't.
The next morning, I got up and decided I would buy it. Why not!
So Saturday came I went back and bought the book and saved about $10 and felt good about it. . . until Christmas morning when I opened the gift from my sister. Can you guess what it was? The book! She'd gone to a lot of trouble to get it for me and paid full price and I had to admit to her that I had bought it a few months earlier.
My prayer had been answered, but I didn't listen!