"The bubble envelopes I use cost about 77 cents each, postage on up to four chips is usually 55 cents, for a total of $1.32, although sometimes the postal clerk gets picky and says the envelope is too thick for that rate, and charges me an extra 20 cents.

My standard End of Auction notice says "1st Class postage in a protective bubble envelope is $1.50, or Priority Mail is $3.20".

Just curious, do you think I charge too much?"

Mike,

I think you pay a little too much for your envelopes. Especially for the number you must be buying. I don't even buy envelopes in bulk and I only pay about 30-40 cents.
Reasonable shipping rates you have but maybe you could trim it a little with careful purchasing.
LOL

BriaN