Target, Toys R' Us, a couple from Walmart long ago (yuck), conventions/trade shows, Amazon, and now my local Toy-Zilla store.
I get new releases from Amazon Japan. For older stuff I either look on the boards here, an app called Mercari, Yahoo Auctions or go to one one of the hobby shops here in the local otaku district.
My collection is 100% retail store bought with a few flea-market buys. My parents don't let me buy online for some reason.
Mostly toy stores (local retail stores Toys R us and Toy Kingdom), very few from various hobby shops.
Most of the time, I shop at retail stores (Like Parkson, local Toys R Us, AEON) and sometimes from various hobby shops for older figures.
Any place that sells the stuff I want at a fair price. That typically includes WM, Target, BBTS, Walgreens, KMart, eBay, local shops, Meijer, Kroger, Ollie's, Ross and sometimes Amazon.
Anywhere I can. Walmart, Walgreens, Target, Toys R Us when it was still a thing, local hobby shops, Amazon, eBay... I'm not picky about where I buy from, as long as what I'm getting is good.
A bunch of places. Walmart, Target, Amazon, Walgreens (if they have an exclusive), BBTS, HLJ (for MPs), Anime Export (for MPs), The Chosen Prime, Transformerland, eBay
You know, I don't really know how they do it. Maybe they made a contract with some dark entity to stay in business forever?
Mainly Walmart and Target, then BBTS or Amazon if I can't find who I want in stores, and then whatever surfaces at Ross or TJ Maxx.