2) There were few buyers for 12.77 at the moment I created that
If there were buyers at 12.77, it wouldn't counter it. Buyers only counter a sale if they are ABOVE the sale(so buyer at 12.88 vs sale at 12.77, you'll exclude the sale at 12.77). This works the same with sellers: seller at 13.55 vs sale at 13.66, you'll exclude the sale at 13.66). Sellers only counter a sale if they are BELOW the sale.
30d Gladiator.tf stats
https://gladiator.tf/sales?item=Strange%20Halogen%20Head%20Lamp&at=2023-03-18T09:54:15.688Z
Sold:
1 @ 12.77 ref
2 @ 12.88 ref
1 @ 13.33 ref
Why are you excluding 12.77?
1) 12.88 has 2 sells
2) There were few buyers for 12.77 at the moment I created that
If there were buyers at 12.77, it wouldn't counter it. Buyers only counter a sale if they are ABOVE the sale(so buyer at 12.88 vs sale at 12.77, you'll exclude the sale at 12.77). This works the same with sellers: seller at 13.55 vs sale at 13.66, you'll exclude the sale at 13.66). Sellers only counter a sale if they are BELOW the sale.
12.77-13.33 should be fine for now.