You can charge a rehoming fee on CL, in fact it's recomended. The question becomes how much is a rehoming fee versus buying a dog. The breeder should know what's going on and since it's still up CL probably doesn't see an isdue with the fee.
Misty- Samoyed Mix, Tannor- Golden Retriever CGC
Robyn- GSD CGC, TC, Midnite-GSD CGC,TC, Brennan-Golden Retriever CGC, Batman-Husky/Greyhound , Apollo-GSD