Try Google.
But, in general:
Once upon a time, eBay had the Trading Assistants program, and that didn't work out. They later tried again with eBay Valet and that also failed. The fact is, that selling things for others has so many problems and pitfalls that very, very few people will do it.
The first problem is that people nearly always have an unrealistic idea of the value of their stuff, so a lot of emotional drama develops. The sales will be on the seller's 1099K, so he will have to do extra bookwork in regards to his tax filing. Then there are questions such as: "How will you and the seller handle the refund when a buyer waits 179 days and then files a claim with PayPal or does a credit card chargeback?" Are you willing to wait 180 days for your money? If not, will you guarantee to cover the loss if this happens? How will you guarantee that? Or, "Who eats the loss if a buyer gets a refund but the returned item is damaged or a sorry substitute is sent?"
And those are just a couple of issues, out of several equally serious ones.
So, the chances of your finding anyone who will sell for you are slim to none. Sorry to be discouraging.
If you do find someone, be sure you have a clean, clear, detailed, written contract.
