Hi Laurie

Here is a simple example. The price is hardcoded here. What you could do it to fetch the price from a custom xml field on your Umbraco product node or what ever way works for your case.

using TeaCommerce.Api.Dependency;
using TeaCommerce.Api.InformationExtractors;
using TeaCommerce.Api.Models;
using TeaCommerce.Api.PriceCalculators;
using TeaCommerce.Api.Services;

namespace CustomShippingProject {
  [SuppressDependency( "TeaCommerce.Api.PriceCalculators.IOrderCalculator", "TeaCommerce.Api" )]
  public class CustomOrderCalculator : OrderCalculator {

    public CustomOrderCalculator( IVatGroupService vatGroupService, ICurrencyService currencyService, IShippingMethodService shippingMethodService, IPaymentMethodService paymentMethodService, IShippingCalculator shippingCalculator, IPaymentCalculator paymentCalculator, IProductInformationExtractor productInformationExtractor ) :
      base( vatGroupService, currencyService, shippingMethodService, paymentMethodService, shippingCalculator, paymentCalculator, productInformationExtractor ) {
    }

    protected override decimal CalculateOrderLineUnitPrice( OriginalUnitPrice originalUnitPrice, OrderLine orderLine, Currency currency, Order order ) {
      decimal price;

      if ( orderLine.Quantity < 6M ) {
        price = 5M;
      } else if ( orderLine.Quantity < 11M ) {
        price = 4.5M;
      } else {
        price = base.CalculateOrderLineUnitPrice( originalUnitPrice, orderLine, currency, order );
      }
      return price;
    }

  }
}

Kind regards
Anders