Zwift on a Budget

In the last month or so I've found myself getting into Zwift, the online cycling game. Last night I attended one of their events, where I ended up demonstrating racing in front of a large crowd (who were mostly looking the other way), and showed conclusively that turning up late to the race start with no wifi isn't a brilliant idea! (Much respect to the colleague who managed to build his computer for me in the 4 minutes before the race started and managed to get me starting only 15 seconds behind the main pack!)
A few people have been concerned about how much it might cost to run Zwift, particularly if you're going to end up leaving the computer in the garage for ease of access. So I thought I'd document my setup to show you can run it on fairly old kit.

Computer

Core 2 Duo E8400

This computer is over 8 years old and I was considering getting rid of it when I built my new one, but it's ended up in the garage to replace the laptop I used to take out there (which was fine for TrainerRoad and Perfpro but not enough for Zwift).
I've seen refurbished E8400 systems online for about £90; you could probably go cheaper in the local classifieds/Gumtree.

Graphics

NVidia GTX460

If you're going to spend money for Zwift, the graphics card is probably where to spend it. The graphics card I had in my machine (an AMD 4850) was surprisingly powerful for a card nearly a decade old; however it was just too old for the Zwift coders to support despite its power.
I eventually relented and replaced it with the NVidia GTX 460, a 6-year-old card which cost me £25 on eBay. It's quite capable of running Zwift smoothly at 720P HD - frankly if you can see higher resolution than that then you aren't pedalling hard enough. Zwiftalizer shows some benchmarks for different cards; you want to make sure you'll be 30 frames per second at least.

Donated Monitor

For a while I used a free donated monitor that was being thrown out; recently we upgraded our TV so I mounted the old one to the garage wall. TV resolutions aren't usually as high as computer ones but it's certainly good enough for Zwift at 1366x768, and it's properly immersive having a big screen in front of you.

Turbo

Zwift supports a wide variety of turbos. Obviously the premier experience is with a 'Smart' turbo such as the Wahoo Kickr, but they aren't cheap. DCRainmaker reviews all sorts of turbos and is your best source of advice for the more expensive end. Alternatively you can use a power meter if you already have one, and any turbo or rollers you like - but that's also not cheap.
If you want to go cheap, try to use one of the few trainers supported by zPower (Zwift's virtual power algorithm with acceleration), or at least one where Zwift includes the power curve (listed as Virtual Power). My Cycleops Fluid 2 trainer (13 years old) is zPower supported and they currently run for about £100 second hand.
'Dumb' trainers interface with Zwift by means of a rear-wheel speed sensor. An ANT+ speed sensor will cost you about £20 - though for ease of use it may be worth springing for one of the Garmin hub ones that doesn't need a magnet (£30).

Other kit

If your sensors/turbo connects via Bluetooth you can use your mobile phone to transmit the information up to Zwift - though I find the app can sometimes get disconnected so I'd prefer something more reliable. Most people use an ANT+ stick - if you have a Garmin, or Adidas SpeedCell etc you may already have one - otherwise they cost about £10.
And lastly, theoretically optional, is the fan - though I warn you that Zwift can make you work very hard! There's usually a decent puddle under my bike after a race. I use a cheap (£15) pedestal fan from Argos but there are all sorts available - my garage isn't too hot in the winter; if you're training indoors then you might want something a bit more powerful.

Hopefully that's of some use - feel free to post other suggestions here or ask for more info!