I have had much success using the smaller stamp auction sites. These sites, where put together, with the idea of buying just the single stamp that you need.
I am not advertising, these sites, but just trying to be helpful.
These sites do not charge the sellers any fees whatsoever, so the sellers have no outrageous shipping and handling fees. Most charge the actual cost of shipping the stamps, which usually runs about 50 cents, and most sellers will combine your wins, within a week or two, and charge just on shipping cost.
I have had many pleasant dealings with these sellers, who are really just collectors, selling off their duplicate stock, and they are not dealers, ( which you find on eBay
) doing this as a business.