As others stated it is not easy to set a price. Claymore is right, a Marushin or MGC M16 modelgun is much better than the LS kit, but your kit is in almost "new in box" condition, so a LS collecter may be willing to pay 200 to 300 € right away.
I would love to add it to my M16 collection, but right now everythinmg is a little upside-down and I cannot afford it.
You could always try eGun.de, but I think collectors being interested in this kind of models are getting rarer there, so your best bet may still be ebay.
Here is also a good place as forum members may be interested as well.