Yikes! I'm in almost the exact same situation with roof and insurance. However, I found a carrier and can push the roof replacement down the road for more lean times in the economy.
My $0.02: I echo everyone's sentiments for the OP both for blowing the budget and getting it now as well as saving/waiting. Everyone has valid points both ways. I just want to point out some things from personal experience on my end. I'll be paying some interest due to financing a portion of my pool being built this year. Also, waiting for the right time to build the pool is a little like trying to time the stock market. If we all could predict we'd have the money and be able to build a pool when the market was softest, everyone would have a pool and the builds would be super fast and efficient. Just like timing the stock market, if it could be done consistently, we'd all be rich. Plus, if your broker/advisor knew how to time the market, they wouldn't need your money to invest, they'd have made more than enough to just invest themselves.