I've never used store-bought juices. Of course fresh is best, but the point is to get more greens in you; so I say do what you can.
How about frozen fruit?
Also, citrus fruits are usually not too pricey, and bananas, no? Here in Cali, citrus is pretty cheap -- actually, most fruit is cheaper
because we excel in migrant-worker exploitation. So we're pretty dang lucky, I guess!
What is less expensive there?
Another good tip for buying fruit is the too-ripe fruit they sometimes bag and sell as discounted because they are ready to chuck them. You could buy those and freeze.
Buy what's on sale and freeze.
Also, you can add sweetener, if that's the issue with flavor.
You can use less fruit that way.
I also use very little fruit because that's the way it's evolved for me; however, I still need to sweeten it. I choose Stevia. Stevia is not good alone; but if you add it to fruit (works especially well with citrus) it's a great sweetener.
You could use half the amount of fruit, add stevia to sweeten. It comes in tinctures or powder. It may cost a bit more at first, but, you use only a pinch of it; mine lasts a long time. It's somewhere in the hundreds-times sweeter than sugar.
Stop buying chips and chocolate and buy fruit