When the real estate market is down, in most of the cases the prices of properties becomes very low. You can invest in a down real estate market, but many people are afraid of investing an amount in a
The cost issue is a matter of roof design and the square footage of the roof. A simple L shaped 1-story, low-pitch roof (typical rancher) is going to cost about $2.75 to $3.25 per square foot to replace (pull up all shingles, felt paper, replace all flashing, drip edge, roof caps, vent boots, install new felt paper, new shingles, etc.).
If it's not leaking now, and you can get by until you raise the roof, then do so.