Weight changes shipping costs. Beside your assumption thoughts, what are you basing your no cost difference on? He didn't have to change it. He offered you $5 savings he did not have to do. If he would not change the shipping as requested, would you you have paid $5 more for the pair of rims otherwise?
No assumption involved... I can ship two rims for the same price as one, and have done so. Why can't he? I've shipped cymbals weighing much more for $15 to California from North Carolina.
Point being, that by only reducing the shipping cost by five dollars, he is admitting to making money off shipping charges.
I chose not to participate in that.
It's like seeing a drum key up for auction with a $4.50 shipping cost. It's a rip off, put it in an envelope with a stamp.
I recently received two 16 inch rims, two 13 inch rims, and 40 tension rods all in the same box, shipping cost on the invoice was $9.50.
Of the six cymbal stands I have shipped recently, the most expensive was $16.... any of those outweigh two 13 inch rims by ten times or more.
Just received an Earth Ride weighing 13 pounds ... shipping charge was $19.67 USPS Priority Mail... again outweighs two 13 inch rims by 11 pounds.
We can conduct a little experiment to prove my point if you wish?
Send me two 13 inch COS Slingerland sticksaver rims via whatever method you wish at no cost.
If I can send you back one and postage costs the same, I keep the other one for free.
If not, I'll send you back the other one.
Wanna try?