gistfile1.txt

ActionView::Template::Error (undefined method `cost' for nil:NilClass):
    1: <%= payment_service_for(
    2:     Time.now.strftime('%Y%m%d%H%M-') + current_user.id.to_s + '-' + @product.id.to_s,
    3:     Rails.configuration.payfast_merchant_id,
    4:     :amount => @product.selling_price.to_f + @product.ship_methods.last.cost.to_f,
    5:     :service => :pay_fast,
    6:     :credential2 => Rails.configuration.payfast_merchant_key,
    7:     :html => { :id => 'payment_form' } ) do |service| %>