Farming drakes and obsidian doesn't sound exactly free to me, but it doesn't sound very expensive either.

The thing with frost arrows and Biomass (its new name) is that you can use any bow with them since majority of the damage comes from the arrow anyway.

Either way, Spine Snap's durability it's a huge concern even now, or at least not any bigger than that of Jotun Bane for example. Arrows only stack to 100 after all. It's somewhat problematic at bosses, especially the Queen, but magic and crossbows can also be put to use.