It's better to eat seasonal things as they are affordable.  Of course sweet potatoes and bananas,eggs are rich source of nutrients and may be bought at affordable prices.

Many are under the wrong impression  that all the healthy foods are expensive. Most of the foods given in the list are available in all the seasons. I eat sweet potatoes raw. As the nutrients are available only in the outer skin of sweet potatoes.

There are many such indigenous foods which are available locally and even in my locality there are some fruits and nuts which are healthier though I have no knowledge about its English versions, still the well known healthy foods are costly but there are many indigenous alternatives which mentioned in the above connected link in this thread.

Yes. the link has given  quite good number of foods both inexpensive and nutritious.

Choice of foods especially of local production is important in order to create a secure health from diseases.

Some foods mentioned in the list are available in all seasons

I believe that healthy food is cheaper. The more costly dishes are just to satisfy taste and may even be injurious to health. 

Gulshan Kumar Ajmani wrote:

I believe that healthy food is cheaper. The more costly dishes are just to satisfy taste and may even be injurious to health. 

 

Exactly sir.  Compare the cost of a sweet potato which is cheap and healthy with that of a pizza which is expensive and injurious to health.

Nope it is not necessary that they are costly. Right now many green vegetables are available at very cheap rate. As SJ said, we should go for seasonal food.

Why Seasonal fruits to be preferred ?

 Here are the reasons.

Any foods which are available in their seasons will be available in fresh condition. In the case of a non - seasonal fruit, the trader has to preserve them to look fresh, the trader uses artificial methods of preservation which robs away the nutrients in the unseasonal fruit. Additionally the traders increase the price. Your wallet will be taxed.

This way the consumer loses both money and the Nutritional values.