Adventures on eBay

I decided recently to stop attending my correcting codes class and get the book and study at home instead. Easier said than done: the school library lest you borrow the book just for the day, only to copy it (don't excpect me to come to school once a week and study here like a nice little girl, I can't concentrate at school outside of class). You can't buy it in Poland. You can buy it on Amazon for only 140$ + shipping. (Err, yeah, I'm talking about "Error control coding" by Lin & Costello.)
Luckily, I found it for 55$ on eBay (+28$ shipping, but that's still a lot cheaper). Immediate PayPal payement was required, but I hve a PayPal account, so there was no problem. At least I throught so.
The shipping price to Polande wasn't given on the listing page, but I emailed the seller, he said 28$, cool. Clicking "buy it now" lead to a mistake: it couldn't calculate shipping costs for my location and wouldn't let me fill them in by myself (bravo eBay!), so it wouldn't just let me buy the book.
Another mail to the seller, and he sent me a PayPal bill (!!!) instead of modifying his listing. Guys, NEVER fall for that: that's a transaction outside of eBay (because the book would never appear in my eBay as bought by me). Not only these are forbidden, but they are really unsafe. Once you send the money, what's gonna make the seller send you the item? What if he doesn't? What if it "significantly not as described"? Maybe PayPals buyer protection program could help you, but on eBay, nothing could be done. Not even a negative comment. (And if you brought another item just to give him his neg, it would most certainly turn against you.)
So, another mail to the seller, he cancels his bill but I still can't buy the book. Luckily, I found another one on eBay for a comparable price. If I can't even communicate with the seller about a technical detail, things can get very ugly. Not worth the risk.