Creaky Hardwood Floors in Rental

[Wale Dada]

In the process of converting my primary residence into a rental property and thinking of the repair items that will make the property most appealing to tenants. A personal peeve of mine are the original hardwood floors that came with the house (detached 1,100 SF single family built in the 1960s) ... they creak loudly even when you tiptoe! 

So I'm debating: do I replace the entire thing with new OSB subfloor and new vinyl plank flooring (contractor estimate of $6K) or is there an alternative fix that is more affordable but significantly dampens the creaking?

Looking forward to your thoughts BP family!