I can get it cheaper elsewhere
This is true so convince them that your service is superior and worth paying extra for.
Explain the fine details of your offer that will add to your customer's profits or how it will simplify things for them. You are already in front of the customer so they know you, and hopefully trust you.
Impress upon them the importance of a good relationship - you will always be there to help iron out any problems they may have. They buy the product or service and they also get you on their side.
