How much has DUP support for PM cost us this time?

Responding to the DUP Deputy Leader Nigel Dodds suggesting his party will back the Prime Minister's deal if she scraps the backstop, Best for Britain supporter Tonia Antoniazzi MP said: 

“This is a betrayal of both Leavers and Remainers.
“They’ll be backing a deal that poll after poll suggests is absolutely not what the country want – and which only two weeks ago suffered an unprecedented and historic defeat. This is not in the national interest and the EU have made clear their refusal to negotiate the backstop again and again.
"The DUP need to come clean and tell us - are they going to u-turn and back this awful deal? And how much has their support cost us all this time?"