Green coffee is processed and dried coffee seed that has not yet been roasted. A home roaster usually buys it in much smaller quantities than an importer or commercial roasting business. Each stage of distribution adds handling, so a low headline price is not the only useful comparison.
Look for information about origin, crop or arrival, processing and storage. The fact that green coffee generally keeps differently from roasted coffee does not mean it remains unchanged indefinitely. Damp conditions, poor packaging and long storage can undermine a purchase before your first roast.
Buy a manageable amount of one lot while learning your equipment. A consistent supply makes it easier to compare batches without changing the raw material at the same time. Keep the unroasted coffee in appropriate dry storage and follow the supplier's guidance. Record the green weight and roasted result, then evaluate the cup after a consistent resting period. The objective is a repeatable learning process, not the largest sack you can afford.
The conversation
A good question can make a better brew.