Hello. I have not been to a fertility clinic yet but I have done a tone of research on clinics and spoken with my insurance company about what they will and will not cover. Once i get an official "infertility" diagnosis my insurance will not pay for anything. Right now I don't ovulate or have periods on my own so my OBGYN is using the billing code for "primary amenorrhea" for my testing. If my OBGYN orders and HSG as long as it is "diagnostic" for my "primary amenorrhea" my insurance will pay for it like any other diagnostic imaging. If I get sent to an RE my insurance will pay for the consult with the copay but stop paying if I get an infertility diagnosis. Ask your hospital about their financial aid options. You may be able to get a good discount on the HSG if you are willing to pay upfront.
I live in a small state so I have very few options for clinics. Basically three private fertility clinics in the whole state and two hospitals in the whole state have REs. One of the private clinics offers a free consultation which I am thinking about, so perhaps that is something to look into. Also, often private clinics are involved in clinical trials of new medications and techniques. For those who qualify for the trials they get the services as a high discounted rate. Usually the trials are advertised on the clinics website. Also, once you get to a clinic you will have a clear plan for cost. One clinic offered a package deal for IVF and if a client did not get a BFP with the first two IVF's the third was free. Many clinics offer low interest loans or you can just save up for what is needed, get an extra job etc.
Good luck with everything, so sorry for your troubles. Infertility sucks and its not right that many insurances will not pay for treatment. Right now I am working with my OBGYN and taking Clomid. I have been researching clinics because I know that may be a need in the future.