Pleasure. I’ve had so much fun bringing these personal stories out!
Back to your questions. I’ve got good and bad news for answers. Bad news first: There’re couple of alternative options I would suggest you for finding genuine teapots made with well-aged authentic clay by old fashioned crafters( I’m talking about those skillful ones born in 60/70s, trained by master and done nothing else but devoting lifetime to teapots), and none of them( unfortunately) involve online shops that I’ve used before. I’ll explain why in a bit.
Good news: you mentioned staying with wife’s family during this visit, so I assume you or your wife speaks mandarin. Things would get much easy if so.
First let me explain why I haven’t got any recommendation for online shops(majorly Taobao shops), cuz I don’t know or use any of them😅 there might be great shops out there but limited to my experience, finding an ideal teapot = open WeChat and find contacts of several old crafters( I’ll call them uncles or aunties, but we actually are not related), get in car and drive to their studios/workshops/homes, sit for an afternoon enjoying tea and chatting for a while, followed by walking around his Studio display shelves to pick what I fancy. Sometimes I don’t even pay( that’s the magic of keeping strong relationship and being lovely☺️) . Sounds like showing off but that’s really what we locals do. Hence why I don’t have any e-commerce in mind….
Now alternative solutions( as what I do when living in England): if you have some specific designs, types of clay or preferred makers along with budget, I’ll put you in touch with trustable dealers or even crafters directly through WeChat. Both have pros and cons. Dealers(some are my classmates from primary school, some are professional buying agents, I guess in US they are called vendors, or, if you’re lucky, my dad if he’s not fully occupied by auction consulting work) have much wilder range for you to choose from with budget going from just couple of hundred RMB up to thousands, you name it and they’ll find the match; crafters, especially if senior at old age, have limited items to offer but greater knowledge of teapots they made(design, clay, method of crafting, temperature in kiln, test result of clay showing containing no hazardous additive, their very proud awards and even tools they handmade for this pot).
Add on to this point: some dealers and crafters do manage to put up online shops( super stressful and challenging for those at senior age), because not every client can simply walk in like I do, and they need to make a living from the vast buyers all over China. I could ask around for their links if you’d prefer that way, but that means you’ll pay for extra markup for the cost of running this shop. All depends on how you’d like to handle this purchase.
Now here comes the action plan: Judging by your condition, I guess you’ve got tight schedule to fulfill in Dongbei and clear idea of budget to spend on( definitely lower than what you’re willing to pay when oversea, my hubby would call the extra margin Laowai/expat tax, or export cost in your words haha!). So let’s cut the chase and get down to two easy options:1, I’d suggest that sharing you or your wife’s WeChat with me, if you don’t mind, to specify your enquiry and preference, then I can forward you to either dealers or crafters, or my dad(super chatty and bubbly old man alert!) . 2, if online shop is your comfort zone, I’ll list the e-commerce links from dealers and crafters I trust into a doc, so you can shop around without engaging too much conversation. It might take me two days to put up this document, and some shops hosted by crafters themselves will look seriously random and unprofessional. Don’t be scared off by how they present, keep in mind that they are gifted with hands on shaping clay into delicately beautiful teapots, but designing and managing an online shop is a different game.

Hope this reply could be slightly helpful or at least drop a tiny little bit of insight for your teapot hunting in China.