Q. I really want to straighten a gap in my teeth which has bothered me for years, I heard about invisalign from my dentist but he quoted me a price in the region of 4000 pounds which is not something I can afford. A clinic running a special offer have quoted less than half that but want me to pay up front. Is this a bit dodgey? Would I be better to save and go with someone who is charging the normal price rather than gamble on the cheaper option? This is still a massive amount of money for me.