Nice question Caution, I was intended to write about how I collect my boxes, because as I figure, it is maybe much different from how most of you guys here do with you.
Out of my collections (about 15 boxes), only three are local picks. There are a lot of used boxes all over my country as well as many guys that love and collect old radio/cassette. It's not hard to seek for an old box sitting somewhere unused in some old men/women's house near my neighbor. In this way, I can find lot of decent box in low price, but it's not what I would go for because that kind of boxes are usually very bad in condition. (I will explain why later...)
Another way is getting in touch with some collectors in my city, this way, I have chances to know and heard plentiful of great boxes. Sharp 777, 919, Panasonic 5600, A2, Aiwa 950, M70, M90, Sony Cf-88 etc are seen often. The problem is that the prices those collector guys asking are too much for my budget.
Other twelve boxes of mine come from online site, it's Vietnamese c2c platform (not Auction) for people to sell and buy old stuff. you can take a look here:
http://phoamthanh.phomuaban.vn/index.php?mod=list&cat=887
Most of those 12 are boxes that just brought into my country from Japan. I don't know exactly process but as far as I know this is how it goes: some people or companies in Japan collect wasted/secondhand electronic products via local site (like aucfan) or from garbage dump all over the country. They then, fill stuff into containers and sea ship them to those "secondhand countries" in south-east Asia like Vietnam, Cambodia or Thailand. For many years, Vietnam was major market for those secondhand products, but for 2 recent decades, goods are only imported to Cambodia, then brought into Vietnam by dealers who live near country border. Those dealers then re-sell to traders and those traders re-sell to collector/shop/buyer.
This is the way I go for to built my collection, because stuff recently brought out of Japan are far better in working condition than those I can find locally from neighbor, which are also brought from Japan as secondhand, but FROM 20-30 years ago. The prices are reasonable too, my in-decent-working-oder and beautiful shape national 5400, 5700, Jvc M70 ... are all under $100
There're very few flea market in my country as I know of, and at which I know, they almost re-sell things recently brought into country as I describe above.
In my country, there is no garage sale or anything like that.
More about boxes that can be found in my local erea/internet: Sharp is the most common brand, Sony, Toshiba, Hitachi, Aiwa, Panasonic (national) and JVC are popular too. There're great number of top dogs like Sharp 9696, 777, 909, 939 ...., Toshiba Wx-1, Bombeat series, Aiwa 950, 955, 990, 660, 770, 820, Sony CFS-88,99, JVC m70, m90, Fisher 490-492, Conion C100, Panasonic 5500, 5600 .... available, especially those Sharp - so easy to find top model from Sharp (that's why I didn't have any Sharp till now LOL)
I've seen only one Sanyo Mx-920, Pana RX-5350, 4360dft (mine), 5400 (mine), RT-S90 (mine). Never seen a Pana 7200/7700, Sanyo 720, bigben, Aiwa 880, JVC RC-50.
Speak of Japanese electronic brands, National (panasonic) get the most reputation in my country, follow by Sony. Sony is famous for their radio, TV while National is well known with wide range of products, from radio, washing machine, rice cooker to bicycle .... Even there's a saying "last as long as a National".
