Valid question if you haven’t been in 3D printing. Also depends heavily on the country.

In the US, it’s common to get quality generic PLA for $15 per kg. Buy several spools at once in a package deal and the price can fall to $11-12 per kg. Wait for a sale and buy a 10-pack and I’ve been getting PLA under $10 per kg. It’s very cheap.

For toys I’d prefer to spend a little more on PLA Pro or Plus, which means it has modifiers added for better impact resistance. This helps a lot with small toys I print for the kids.

I can easily find 4kg for $40-45 online, or if I am patient I can grab 1kg for $10-12 on sale.

You may be looking at more advanced materials like carbon fiber or fiberglass reinforced filament for printing larger parts that take a load/stress.

All I had to do was search "PLA filament" on Amazon and results started at $11USD

2kg packs on Amazon that go for around $20, eSun and similar.