Buying advice: is a Giant GSR400 worth 50 pounds?

[theqw]

Here's the classified description:
Giant mans gsr400 mountain bike. 21.5" frame with 21 gears. The bike has good brakes and is in full working order. Good condition.
Bike looks great in the pictures, except for rusty top handle bars (which I might remove anyway). The person is selling it for 50 pounds, but from what I can gather, GSR400 is an old model - is it worth the price?

Ref: http://www.gumtree.com/p/for-sale/giant-gsr-400-mans-bike/1072568043#photo-content

I'd really appreciate tips/recommendations.

Thanks,

-theqw