USA resident.
Pretty much for a majority of my non third party 5E books, I've only played about 37.99+sales tax for a number of recent DND releases of last year and this year. My go to sites are usually Minature Market and GameNerdz as I haven't had any issues from them. although my Tasha's Alt cover that I ordered from GameNerdz is a no show and Minature Market is selling it for 49.99 for whatever the reason. Although that's probably more because of my apartment complex than GameNerdz being unreliable
I did get Mordenkainen's Tome of Foes from Amazon for 29.99+tax from Amazon. And recently, aside from Tasha's, my DM sold me his extra copy of the PHB, in new condition, for 20 bucks. I was gonna try to get the SCAG for the unnerfed Booming/Green Flame Blade, but I recently got Version 3 of the Spellbook Cards, Arcane, from Amazon so that has the unnerfed versions in it. So I'm not as hardcore about getting the updated SCAG book now cuz of that.
As for my Third Party/Kickstarter backed 5E products? I won't go into the details there, but all I'll say is that I am usually a dice/swag tuls when it comes to those. And its best we leave it at that.
I got Adventures in Middle Earth 5E for 20 bucks too. That was from Atomic Empire. They are pretty cool too.
My recent buying goal now is to get another copy of Tyranny of Dragons. Due to a stupid mistake on my part, my copy is a bit "bent" and that is an absolute disgrace to the epic cover of the book.