Editing photos

We are a small furniture retailer, and we receive images of the products we sell from the factory but in one finish eg dining table with metal base and dark wood top.

We would like to re-touch/edit those images to change the material on the top of the table to show the different finishes/colours available eg change dark wood to another colour wood, or paint finish.

Sometimes we may also want to change the base, or what items are on the table but 99% of the time we just change the table top.

Can you suggest a price per image for a change of this kind?

We have about 10 images now which will need two versions of each, but it is ongoing work
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For those asking here is an exact example of what is required please see:
https://www.dropbox.com/sh/fpj8vpvbih60ol2/AADNAJfq-UB4DRO5kDjRL6xqa?dl=0

Two images need to be edited, the table tops changed on both images, and the table legs changed on the image in which they are visible (table up).