What are the rest of the specs on the laptop? What processor and how much ram, mainly. A hard drive or ssd can be had for $30 to $100. However, if you need to replace the battery at some point, add at least $20. If the power supply goes, that's another $20. If the power jack wears out or breaks, that's another $10-20. All of that is assuming cheapest ebay parts.
Depending on age, it may not be worth maintaining. Otherwise, you can still update it to windows 10 for free, and adding an ssd will make it faster than its ever been.