Don't have a good answer, but you might check Home Depot.
My granite is 3 cm. I got it at a relatively good price. My home was previously owned and most of the builder grade stuff is still here. In most cases, it is being slowly replaced.
Check a local granite company and get what you love. You won't regret 3 cm.

Almost all granite on the west coast is 2 cm. Builder's grade generally means lower, but still acceptable, grade. It could mean very common colors, prefab slabs, or ???

The standard granite around here is 2 cm. I suspect builder's grade would mean the more common and less expensive varieties.

Builders grade stone are of inferior quality when compared to First choice materials. They might have more inclusions, fissures and even machine marks. If you had to compare it to general merchandise, it would fall under the "scratch and dent" department. Builders grade stone is often waaaay less expensive than first or second choice stones.

Basically, it is put on the list just to say "We have a granite option". In a situation like that, they might give the option of choosing between a limited number of colors, and you most likely will not have the option of selecting your own slabs (if they even use slabs and not blanks)

In my area, the larger subdivisions by a single builder (or a group together) usually buy containter loads of pre fabbed granite straight from China. They then have the carpenter try to fabricate it to fit. Some of the results are quite painful to view. Most are merely bad. But, they're able to then use the "granite countertops" buzzwords in their adds trying desparately to entice a buyer. The container loads are usually Baltic Brown, Tropic Brown, etc. The commoner and less expensive granites, and certainly not top quality. They then over use them in every kitchen, so that most homeowners are sick of these granites in the same way that homeowners became sick of oak cabinetry because most builders installed poor quality builder's grade oak cabinets.