A third, possibly cheaper approach, is to sell some roads instead of selling some buildings.
If any of your roads are unimproved paths, you can sell and rebuild them to your heart's content.
If your roads are improved, you can sell them for a loss, but replace them with unimproved paths for free after, deferring the re-improvement for later if necessary.
Just be aware that improved roads provide Culture, so selling roads might diminish your total Culture beyond acceptable levels.