You can sell your items in Sinespace for a discounted price via promotional sales. Promotional sales mean that any silver item you have might be given away freely or included on base starter avatars. If your item is selling for Gold, this may be included in platform based sale events. The promotional sales option is under the Virtual good component.
When you have added the virtual good component to your item, go to the 'Pricing' tab.
To allow use in promotions, check the 'Allow Use in Promotions' box.
You can adjust the Max Discount in Sales slider to whatever amount you want the max discount to be. This setting is percentage, so if you set it to 20, this will be 20% off.
Once you have set this, you can continue to upload your item as normal via the virtual good component.