Coupon codes are a popular search item, much more so in this economy situation. If you are using Paypal as a payment option, you can actually create Paypal coupon codes yourself.
This way, you encourage sales for your merchandise. I used to create Paypal coupon codes for my customers to encourage them to buy again.
For example, after a the client paid for their items, i’ll include a coupon codes for a discount on their next purchase.
You can put a expiry date on the coupon, discount a certain amount or by percentage to promote a repeat buy.
When i was selling on ebay, I used Paycodes to create coupon codes. They charge $24.95 a year, so i think it was pretty reasonable.
Another site you can look at is MyStoreCredit. This is a 3rd party service which create a store credit for your buyers based on the amount they spend on their first purchase.
Customers retention is easy if we think like the customers. Most people like some discounts and gifts. So it never hurt to try as your customers will likely return with the coupon codes, if they like you.