Try to get a vendor to give you product for free or sell it to you at cost (one man's trash is another man's treasure) - and then give it to your customer with their purchase.
Provide consultation services that only costs you time, but that the customer values greatly.
Find a product that your customer needs with your service. Partner with a vendor to provide it and share the profits.
A report or video on a subject your customer likes can boost value. Meanwhile it will cost you a few hours
Put products or services together, that your customer values - but that cost you close to nothing to provide.
Provide more convenience for your customers (open earlier, free shipping, turnkey system, etc.) without utilizing a lot of time or money.
Provide the product or service in a package that your customers value greatly (add all of the bells and whistles).
Provide the product or service in a more beneficial format for the customer (packaged deal versus individual purchases).
Provide payment options that make it easier for your customers to pay (monthly payment versus lump sum).
Add more bonuses for customers that will pay more, less for those who will not (my favorite).