An SSD is the best upgrade you can give your older computer, and Samsung’s 850 EVO line is the most popular one there is. A worldwide NAND shortage has reversed the previously inexorable downward price trend on these things over the past year or so, but today on Amazon, you can score a 1TB drive for $300, the best price Amazon’s listed in 2017.
If you don’t need quite that much space, the 500GB model is priced at $150 right now. That’s $10 more than it was last month, but it’s still on the low end of the price spectrum for this drive this year.