Sounds like a 9 inch tube based set. I'd go with Admiral, just going by the date and the price.
There wasn't a big flood of really cheap (sub $80) sets coming from japan till later on in the 60's, 1968 or so. They were around but not as many as later. Or at least this is what I've found from my research.
What did it look like?
Color of cabinet?
Controls , on the side, on the front right, controls on the bottom below the screen?
Name of discount store?
The more accurate you can describe it the more we can ID it. I've got an ongoing archive of pics of close to every mid 60's portable ever made and I likely have pictures of it.
This is the 1965 - 66 Admiral 9" that was in that price range
