I have no idea really. I can't count the first amiga I got, because that was a gift. But then I had to get a monitor with my own money. That was about £300 I seem to remember. Then 512kb ram expansion, was about £60 here in norway. I also bought a lot of disks (although I didn't copy EVERYTHING, like some people I knew did. I was more picky), controllers (bought two 6-button Megadrive controllers for about £25 each just for Sensi, so I think I could label that under the amiga). Since then I bought hardware and software and accessories for a lot of money.
All in all I think I've spent well over £2000 in total, if you count EVERYTHING up and until today.