There's been a number of scam sites that've popped up, claiming to be a "wholesale" (or other) version of a large online store (e.g. Backwater, SAS, Underground, etc.) in the last few years (and more scam sites in general). They'll likely have several rare species advertised as in stock, some virtually impossible to find, others possibly even illegal. Descriptions can be directly transcribed (sometimes rather poorly) from the original site, and might even be descriptions for an entirely different animal.
I believe there were a couple ads on MorphMarket for chuckwallas last time I checked; I know they pop up there every now and then, but don't seem to be very common.
Good luck with trying to find one! Heard they make decent captives, but never knew anyone that kept one that could confirm.