Variations of 得 in 好玩得很
得很 (very) is for describing a high degree of the adjective. e.g. 鮮牛肉貴得很 - Fresh beef is very expensive
得多 (much more) is for describing a much higher degree of the adjective for one object in comparison to another object. e.g. 鮮牛肉比冰牛肉貴得多 - Fresh beef is much more expensive than frozen beef

If you mean 'very', then '多' in  '鮮牛肉貴得很多' is nonsensical. The sentence itself is wrong. It has to be '鮮牛肉貴得很'

If you mean 'much more', First, you need another item for comparison. And second '很' in  '鮮牛肉比冰牛肉貴得很多' would be redundant.


Either 鮮牛肉比冰牛肉貴[得多]  or 鮮牛肉比冰牛肉貴[很多] would be correct, but not 鮮牛肉比冰牛肉貴[得很多]
In your examples, It would be either 足球好玩得很 (football is very fun to play) or 足球比籃球好玩得多 (football is much more fun to play than basketball)