Some do value pricing, lump sum. It is a good model. Our attempt is to be a valued consultant and to be our client's surveyor. I want them to point at me and say, "That is MY surveyor." or say, "I will need to call MY surveyor."
So our attempt is to bill for actual hours worked on a project, because it reflects that relationship.
No matter how you do it, remember: TRUST is the difference between having fun and making money and losing everything.
We have a similar goal. I simply don't see charging a client the value of a product as a violation of trust...
All good responses here. I will add this: if you give the client a discount on the fee for this project, tell them why you are doing it.
Once you provide a product for less than market value, the client will always expect a "cheap" price on the next project, or else they will think you are overcharging them.
Amen, Brother Scrim, Amen. Yea verily I saith unto you that the truth is evident in your speech.
I had a classic example of that happen to me with a good friend and former co-worker of my wife. I gave him a heck of a deal on a fairly simple boundary survey where he was building a new house. Six months later, his lender insisted on a mortgagee title inspection to verify construction was complete and that the house, etc. was on the correct spot of Earth. I gave him my standard price for those when he called. He immediately reacted badly (a red hair thing) and said that was more than I charged for the survey. The lender had assured him it wouldn't run more than $100. Long story short, I did not do the MTI and we made a point to avoid each other for quite a while.
In the first instance, that old data is yours to do with as you see fit.
That said, a topo isn't much good if you can't lay out the design based on it. If your 4 year old topo work was monumented with wood hubs and MAG nails you may not have any solid control that survives, rendering your old product with only an appearance of value. At best, recovery and rehabilitation of the control is a cost of an update. At worst said rehabilitation may not be possible.
I thought I'd let you know what I did in the end.
I concluded that an agreement I have with a client is confidential. Would the old client want me to go around telling others that I'd carried out a survey for them on the site? This is not for me to decide, so I did disclose that I'd carried out work there before.
I put in a reduced price so I wouldn't look too dodgy in case my previous work there came to light.