I bit the bullet 2 weeks ago and ordered 2 mechanical seals, 2 oil seals and 2 stainless circlips from Zed Parts and yes, the shipping was $34 for the first seal and I was expecting the cost for shipping to jump up significantly, but in the end, it was an additional $5 for the other 5 parts. So a total of $39 for the shipping.
Everybody has to make a buck. Most of the shipping costs are for the 1st item. Adding additional items is just the difference in cost for a larger package and weight.