I do recommend buying a new power meter so you don’t end up with someones old burnt out unit that required calibration but the user hoped that some noob wouldnt yet know about that possibility and was too focused on ‘getting a bargain!’. 😉
I own both a stages cycling and powertap. They are the lightest, cheapest, easiest to service yet still accurate products currently on the market.
A lot of people think that only pro’s looking to peak for an EPO cycle need to use power. The reality is ANYBODY will benefit immensely from having a power meter to pace against on the climbs, flats, hard or easy days. I still check the gauge on my track pump. I still look at my watch to see how much time till sundown. I still floss in front of a mirror to make sure Im floss’n the right spot. I can’t believe it took me so long to get a power meter so I know what Im actually doing on the bike VS what I think Im doing.
If you want to floss better. Use a mirror.
If you want to have 120psi in your tyres each time, use a gauge.
If you want to know how much light is left in the day, check your watch.
If you want to climb hills easier, get a power meter.