Yeah, I have a PTA7 that's so old the plating is starting to lift near the base of the cone and I think it is my preferred tip too.
There are lots of PT tips on eBay for $7 CAD or less but the shipping from the US is higher than I feel is appropriate. Amazon is even worse ("free shipping" just means the cost of shipping is added to the price).
When I gave up on them I spent an hour Googling PTA7 Weller Canada while watching TV with the wife and found a place called ITM Instruments that has them for
4.40eachwithaflatrate17.50 shipping so I ordered 4 each of PTA7 and PTP7 (conical). After taxes that comes to $7.45 each.
That should last me a while.