I get occasional questions about this and have not tried this in my lab but was alerted to an on-line thesis which has successfully used this approach for therapeutic purposes in Alzheimer's Disease models in mice.
UNC is no longer offering single-unit AAV for DREADDs although we expect that these will be available via ADDGENE shortly.
To get onto the ADDGENE notification list contact: Leila Haery email@example.com with serotype and genotype needs for DREADD constructs. She will be helping Addgene coordinate production and distribution of DREADD viruses.
In the meantime, you can order plasmids from ADDGENE and simply ask UNC to make a custom prep for you or send the plasmids to the Penn Vector core.
Alternatively it looks like the Duke vector core is also offering DREADD-based AAVs.