try to avoid altogether the use of the word 'but' - it's inherently confrontational
an old-style technique was to reflect back the objection as a re-phrased question, but in a form that the sales person is confident of being able to answer positively, for example: the prospect says he thinks it's too expensive; the sales person reflects back: "I think what you're really saying is that you have no problem with giving us the contract, but you'd prefer the payments staged over three years rather than two? - well I think we could probably do something about that...