I haven't shipped to Czech Republic yet, but I had to go to the post office before for a few other Eastern European countries (Ukraine, Romania, Russia). The folks at the post office didn't know why either.
In the meantime I did a few shipments with Endicia. Prices are the same as PayPal/Ebay but it also offers First Class international parcels. Can't avoid the price increases, but at least it's still commercial pricing.
As for downsides (besides the $16/month fee):
- The provided desktop application is horrible when using a laser
printer. I printed about 50 pages before I figured out all the label
variations I need. I guess they want you to buy their fancy label printers.
- The account has to be loaded with money upfront, from which
printed postage is deducted.
- They don't support PayPal to pay in, credit card or ACH only. Which is a bit inconvenient given that all Tindie money comes in through PayPal.
Still on the fence whether I will keep using it beyond the 30 day trial.