I cheaped out last year and didn't spend anything on the lawn. Last week I pulled 3 wheelbarrows full of dandelions I hand plucked from the ground and I'm only half way done. Lesson learned. You really need to keep up with it.
I know Ace Hardware rents gas powered thatchers. I might give that a shot and try over seeding. My lawn is huge. It takes 2.5 big bags to cover it well. It gets expensive quick. I used Stein's weed and feed instead of Scott's this year. It definitely greened up the lawn. It was $36/bag I think for the 15,000 sq ft bags.
Jay, where do you buy your seed at what's a good price?