The "gotcha" with this year's USPS rate increases is that 1st Class Packages are changing over to a zone based pricing structure. With 9 mailing zones, the further away you mail something to, the greater the cost. For example, under the new pricing, if I live in NY and mail a 4 oz piece to NJ the price will be the same as now $2.66. But if a 4 oz mailing is sent to CA from NY with the new rates, the price jumps to $3.09. East coast and west coast shippers will experience the greatest increases in prices. In addition, all 5-8 oz packages will cost $3.05 instead of increasing at each OZ increment.
https://postcalc.usps.com/DomesticZoneChart
https://blog.stamps.com/tag/2019-usps-prices/
I have not seen how ebay will handle this, but it will appear that ebay sellers would consider a switch from a flat rate to a calculated s/h cost so that they do not over/under charge their customers. Or pick a price point in the middle.
The new pricing norm for mailing a card(s) via 1st class package may become $4.
For those that ship a lot using this service, thoughts?