Don't conflate people's perception of value with the actual value as they rarely meet and the former generally exceeds the latter. Once it becomes a sale item, that kind of all becomes moot anyhow.
I'd also add that a family connection is not always the value it's deemed to be either. Don't mean this as a dig against the OP, more that not all family connections have value is all. That's another perception thing, just the other way around.
To the OP, if space as at a premium and you have lots of old tools sat in a shed, I'd advise getting them dry and cleaned much sooner than later. Chances are that there is possibly some gems in the larger collection and being left in a shed will detract from that value, either to you personally or to a potential buyer. Take your time, plenty of resource on the web to determine most of the info you need to work out what stays and what goes.
