Both of mine have been under £100 on eBay.

The first had a weird fault that caused battery drain and ultimately the backlight to fail. That was a ***** to diagnose.

The second is going strong.

USB port is the main point of failure. It's so bad I'm surprised there wasn't a class action lawsuit against Nokia. Maybe people just loved their N900s so much.

There are a few ways around it, none of which are great.

I'd look for an honest UK eBayer with a good reputation. When you get the device, test everything: USB, camera, SD, GPS (can take a while), battery drain (search this forum)...

In the UK, if anything is faulty and needs returning, you are allowed to claim postage.