I've used my iPhone 3GS for 6 years from 2009-2015. Only replaced it because I wanted 4G support and a better camera.
Sure it was a little slower than my current iPhone 6+, but it was still fast enough. I used it a lot during those years, and was really happy I got the 32GB model in 2009, as especially TomTom took a lot of my space (I travel a lot, I have Europe, US&Canada, Brazil, Australia, New Zealand and the Middle East offline maps on my phone.)
I still used my iPhone 3GS when I go to a festival or out on the town as it's nice and small and not as expensive to lose as my new one. It still handles WhatsApp and such to communicate with my friends.
I am typing this on a 2010 Mac Pro with 4 core Xeon, Nvidia GTX980, 32GB ram, SSDs and OSX 10.11. It runs great. My 2011 Macbook Pro also gets about 8 hours of work every day, and even my 2007 Macbook Pro still sees regular use.
Apple stuff might be expensive (although in general not much more than a PC with the same hardware). But they last. I even used my uncles iBook from 1999 a few weeks ago (MacOS 8.6!) and that still runs fine.