A pound of apples costs about $2, usually less. For that you get around 10 grams of dietary fiber, or nearly half of the daily recommended intake, plus substantial amounts of vitamin C and potassium. Not the cheapest thing on the shelf (vs cabbage/beans), but with convenience and taste factored in it can be a very practical choice.
And how expensive are, say, carrots? Apples here are 2 eu per kilogram. Carrots are the same price out of season, and carrot season is coming. From what I can tell, carrots beat apples on most benchmarks, except for having to prepare the things.
If dietary fiber is your concern, switch to brown rice and eat some more.
I have no clue what typical vegetable or fruit prices are in the US, but both here and in most Asian cultures known for low obesity rates, fruit is more expensive than alternatives. I don't expect mass produced fruit to break the bank, but realistically it's one of the larger costs.
Anyway I just got back from the store. I bought: 2 pounds of pears ($3.50), 1 pound of carrots ($0.90), 1 pound of celery ($2.00), 1 pound bag of chips ($3.50)
What does that prove? Not much, except that fruit seems to be in the price range of vegetables, and I wouldn't characterize either of them as expensive. The celery was a bit more expensive than the pears, and the carrots were 50% cheaper. Both fruit and vegetables are cheaper than junk food, so if you can afford junk food you can afford fresh food too.
Especially if you change up which fruit you are eating depending on the store’s sales. My local store almost always has some berry or grape for $2 a pound.