Think its determined by what your selling ,this will determin IMO weather the costs involved are worthwhile.
In some instances bigger the audiences means larger fees and doubt Spink would be negotiable
I Know someone who this year bought a large penny collection outright privately and just took everything (no fees) so a number of options.
Depends if you want to sell the collection in one go and how large it is , as maybe worth splitting up.
Sell some privately and see whats left maybe .
As a buyer Neils was definately the best option .