Organic Gardening Material what is ok to usein a grow box

I have a good friend who made the comment "yikes it must cost a
fortune to fill a growbox"

I said no it isnt because you can use a variety of materials such as:

Pine needle (preferably ground up)
Sand
Perlite (a bit pricey)
Sawdust (other than black walnut)
Small wood chips (NOT - JBK)

Ok here is the rub,

Lets say a person has only pine needles, is it ok to use them at a
100% ratio? I would guess 95% of people have access to free filler
of some type.

What are the best ratios?
Is it ok to use a combination of whatever you have on hand?

Thank you for the clarification.

Group:

Yes, it is ok to use what you are able to find inexpensively, so long as it is clean and weed, bug, and disease-free.

Pine needles can be used - even 100% if necessary - but they really need to be ground up! Run them through a chipper/shredder a few times, or use a hammer mill. They are best, as are all of the other organic alternatives, if you have 30-40% sand in the mix. This is because the sand helps with drainage.

Most any combination of organic materials can be used, so long as you have 30-40% sand (by volume) in the mix.

Here in Armenia I used just 25% sand recently for growing in the seedling greenhouse, and because our wooden trays (aka flats) didn't have wide enough spaces between the wooden bottom slats, they did not drain adequately, and the plants suffered. We had to re-plant using more sand. And we also re-did the flats with spaces of almost 1/4" between each slat. I had allowed the flats to be made with only 1/8" spaces the first time, and when the wood swells it leaves a too-narrow space for good drainage.

Do not use wood chips in your soil mix. Make sure you use only sawdust.

Jim