If they are calling you, the hard work is already done. They know the listed price isn't attracting the help they need and they're digging deeper to find it. They need your help to get the job done. Ask for the price you want.
It's like this. Your report - and those produced by others like you - are the only product they have to sell. They don't make widgets. They don't grow peas. They sell what you make. If you aren't happy with the price they offer, say so and hold out until you are. They may balk and walk away to prove a point. They may do that the next time too. Ultimately, they can't grow or make their product. So they have to make a deal with somebody or go without.
They have to purchase it from you and me. We are the only source for the product they sell. So if your price is fair and it's what you need, don't budge. They will pay it or they won't. They may buy from me instead this time. But I am also insisting on a price I can live with.