Thats a fantastic collection, many years worth with items from before my time and I was collecting 20 years or so ago.

I've sold a few figures on ebay and you will get a bit of money for unpainted ones. Painted ones aren't usually as valuable as you can't always paint over them and keep a good quality. Its hard to tell from the pictures but the condition is key. Also, the rarity of them too. You get specialist figures and ones that weren't around for long, like figures that changed spec or got quickly phased out.

That is a very good collection there with all the boxes adding to the value of it. Unless you get a good offer for the whole lot you would be far better selling individually or possibly even donating it.

There is easily many hundreds spent on that and probably well over a thousand - never mind the many hours spent on it.

It might be worth getting in touch with a club or group. There are usually ones linked or organised by the local Games Workshop and I'm sure there will be guys that would be interested in many items from that collection.

What are the items in the boxes like? Some of those tanks may be worth something.