Hi Redmoon,
I know that the dealers will advise you to sell the group as one lot, and that may well be the EASIEST way to dispose of the whole group. However it is not always the best. After all, they are dealers and to make a profit, they will sell them on at a fair mark-up to collectors.
Selling individually on eBay etc, can sometimes get good prices for individual items, particularly known and collected examples e.g. Paul Ysart. It can also take a lot of work.
The third way, as someone has already mentioned, is to try and group them into manageable numbers (say 20), group them as much as possible by maker, and then post pictures of them here. Invite interested parties to contact you. Many collectors will pay good prices for individual examples that they want/need for their collections and in order to secure these will buy a group of similar items.
There is nothing to lose. If unsure about a fair price for any particular example, you can always ask here and someone will advise you ( with a little caution and without guarantee). After using this site, you can always fall back on eBay or dealers to clear the rest.
As an example, I collect Whitefriars. Another member may well be an Ysart collector. By showing the specialist collectors what is available, you may be able to get a better return for a group of weights within the total collection that you have.
Valuations for insurance can be at least double what they would bring at auction. The valuers have to allow for replacing the item and include sellers and buyers commissions plus transport costs.
All the best,