Spending nearly $400 on a nine year old computer is something of a risk in my opinion. A few hundred more and you could find a refurbed 2015 or newer MacBook Air or even a new one when Best Buy runs one of its sales. That said, from MacSales the RAM upgrade will run about $70 and a 500GB SSD about $160. I can also highly recommend Crucial Tech's SSDs. You may find slightly lower prices shopping the discount stores but MacSales components are topnotch and their customer support is second to none.
The speed of your 2009 computer is constrained by 3 things: the CPU (its brain), the amount of RAM you have, and the speed of your hard drive. Starting in 2011 Apple began installing SSD drives in their top end computers and MacBook Airs. Instead of storing the data on a spinning magnetic platter an SSD stores data electronically in RAM that holds its memory when the power is off. And SSD is incredibly fast. Years ago when I upgraded my 2009 MBP with an SSD it was like I’d bought a new more powerful machine and it gave me several more years of use from it. You want an SSD - while the SSD and RAM upgrade together are a huge win, I found that the SSD alone gave a bigger speed boost than the RAM upgrade alone.
The data doubler item that MacSales sells lets you replace the DVD drive with another drive. I know many people who upgraded their system with an SSD and a standard hard drive. This made sense when a 128GB SSD cost hundreds of dollars but the power user needed much more storage. The cost of SSDs has plummeted and given that the data doubler configuration can be finicky I don’t see the sense in it today.
If you feel more comfortable letting someone else do your upgrades, that’s up to you but neither the RAM or drive upgrades are difficult. I’ve taken students with no experience at all and trained them in a see one do one approach in 15 minutes to do both tasks. If you have a second computer or smartphone so you can watch the video as you go it should be a no brainer.
