If you are truly wanting to start a reputable business, then you should hire a IP attorney to advise you and help you prepare the necessary Work for Hire, Independent Contractor and Licensing/Sales Agreements There is much more to this than wanting "to pay the fee once."
If you will be receiving original images from various artists, the artists will be the authors and thus owners of the copyright. If you want to register those copyrights in the name of your business, you will need an assignment from the artists. So one possible business model would be to purchase the images from the artists and then license them to your customers.
Assuming you get past the first hurdle of copyright ownership in the images, you are permitted to register multiple images as a collective work. But if you are not selling the images as a collection, then you are not going to be getting the right protection. Copyright registration can be done online for a modest fee of $35. It is worth doing right.
To do this right, you really need to hire an IP attorney. While it will require more cost up front, it will save you money and headaches (and potentially legal problems) in the long run.
The statements and views expressed in this posting are my own and do not reflect those of my law firm, are intended for general informational purposes only, and do not constitute legal advice or legal opinion. This information is intended for informational purposes only and should not be relied upon without independent consultation and evaluation by an attorney. This information does not create an attorney-client relationship. Please consult an attorney if you have any questions about the subject matter of the information above.
This could certainly be done through the proper assignments and agreements. Get an intellectual property attorney to make sure you set everything up the right way.
I hope that this answer helps you in a general sense, but it does not constitute legal advice, nor tax advice of any kind, and does not create an attorney-client relationship between you and myself or my firm.