One way is to accept barter offers for your product. Maybe the person can't afford to buy your product. They may have something you could use in your business or personal life. If the barter deal isn't fair enough, either of you could add in some cash. You may not make money but, they might buy other products you offer.

Another way is to include a negotiation offer at the end of your ad copy. Tell your reader if there is something they don't like about your offer, they could contact you and negotiate a different buying offer. They may not like your price, guarantee, shipping methods, payment options, etc. You can gain a potential lifetime customer by being flexible with your offer and negotiating instead of loosing them.

A simple way to attract lifetime customers would be to give people a freebie. The freebie should be related to the other products or services you sell. You may not be getting paid for the freebie, but you will get a lot more people using one of your products because it is free. If they are impressed by your free product there is a high chance they'll buy your other products in the future.

The last way is to sell your product at the price it costs you to produce or buy it. You will usually sell more products at a lower price than your competition which equals more potential lifetime customers. You will break even in cost but you'll make your profit from the upsell and backend products your sell your lifetime customers.