Hi Prince,
The best market for retro furniture is eBay. The best way to get an idea of the value is to look at eBay completed listings. If you can find something similar you will get an idea of value.
It sounds quite a cool sofa. Corner groups seem to sell quite well. A Danish corner sofa from the 70s sold for £650 recently. It's all down to desirability of the design and condition.
See [
cgi.ebay.co.uk]
regards
Retrowow