Prescriptions

1) Dispense with Andameds or another wholesaler when possible. This resource should let you look up the manufacturer cost of any medication. CostPlus Drug Company is a great option.
2) Avoid using "plans" which inflate & hide prices through PBMs.  If you do use a PBM, rely on this white listed transparent group of PBMs highlighted by the National Community Pharmacists Association.
3) GoodRx and Blink Health and SingleCare are good free “coupon” (transparent pharmacy benefit manager) options for obtaining fair pricing at large pharmacy chains on generic medications.  Local pharmacies often do not participate in these programs but you may still use them as a reference price when speaking with a local pharmacist. Medicare patients may want to use this calculator to decide whether part D coverage is worth purchasing. If you are lucky there might be a third party free pharmacy in your community that does not work with any PBMs or insurance companies (like GenScripts in Tulsa, OK).
4) Sometimes small mail order pharmacies are the best option, examples include GenScripts (OK) & Marley Drug (NC) (such as Zypitamag (pitavastatin) at $1 per day with no prior auths or step therapy with Medicure)
5) In the rare scenario where generics are NOT an option using NeedyMeds as a source of aggregated ways to obtain discounted medications (often from the manufacturer) for your patients can be helpful.  If the patient does not qualify then medical tourism might be an economical option, even the CDC realizes this industry is growing.
6) Vaccinations are often available at low cost from health departments.  Some pharmacies (such as Costco) are starting to display pricing.
7) Some patients decide that it makes sense to risk going international.  Planet Drugs Direct is one well known example.

Labs, Path & Radiology

Laboratories: 
Quest Diagnostics (with an example from AtlasMD) 
LabCorp
BioReference Labs
Tribal Diagnostics (they have an excellent price transparency pricing page)
Local labs - might offer competitive prices  

Pathology:
Aurora Diagnostics
Cole Diagnostics

Radiology:

Ascend Imaging Center (Southfield, MI 48034)
SmartChoice MRI

Many listed as Kempton Premier Providers
 

Surgery / Specialty

There are lots of transparent pricing resources to choose among.  Their accuracy and helpfulness often varies by geographic region:
The Source (on Healthcare Price and Competition)
ClearHealthCosts.com
DocCost.com 
The Wedge of Health Freedom (may be a good way to locate like minded specialist physicians for referral purposes)
Banner Health contains links to internal and external prices
Atlas Billing Company

Emergency Rooms often force patients to litigate to achieve fair prices. Patients will almost always win, but they must be willing to take the time and effort to fight the hospital. These law review manuscripts are an excellent resource:

Nation, George A. III (2005) "Obscene Contracts: The Doctrine of Unconscionability and Hospital Billing of the Uninsured," Kentucky Law Journal: Vol. 94 : Iss. 1 , Article 5

Mark A. Hall & Carl E. Schneider, Patients as Consumers: Courts, Contracts, and the New Medical Marketplace, 106 Mich. L. Rev. 643 (2008).

Medicare prices by region can be a reference point as well. 

HITECH (full explanation here) requires physicians to offer cash pricing to patients that want to keep the information private from their "health plan."  This includes Medicare, though the Medicare limiting rates still apply when the patient pays the bill, and the physician is free to offer a rate less than the Medicare amount to any patient.  A detailed explanation is included in the Federal Register from pages 5,623 to 5,634.  Here is another helpful resource from MGMA.

The Final Rule from the Dept of Labor and HHS requiring co-pay transparency from hospitals and insurance companies was released in late 2020 and is scheduled to start taking effect from 2021 to 2024. There are many legal challenges expected. Excellent overviews of the “final rule” are provided by Ropes & Gray and Venable.

Dermatology:
Bluebird Dermatology (Spring, TX)
Kittridge Dermatology (Pittsburgh, PA)

Endocrinology:

Ethos Endocrinology (Houston, TX)

Gastroenterology:

The Modern Med (Palm Beach Gardens, FL)

Podiatry:
Pacific Point Podiatry (Tea Nguyen, DPM in Freedom, CA)

Rheumatology:
Diana Girnita, MD, PhD (CA, OH, KY, IN)

Ophthalmology:

Ami Shah Vira, MD FACS (TX) (Neuro-ophthalmology and Oculoplastics)
Perceptron Health (NY) offering equipment (video demo) for diagnostic retinopathy screenings that can be taken in your office with images reviewed remotely by optometry or ophthalmology. “We charge $20/read and typically $180/month for the camera lease. But we’d be happy to provide leases for $130/month to anyone coming through DPC Frontier.”

Psychiatry:

Coral Psychiatry, (IL, MA, NY)
Kate Salama M.D., Reproductive Psychiatrist (Denver, CO) (NY &MA)
Vitality Wellness Institute (Interventional Pain & Addiction) (San Diego, CA)

Hospitals:
St Lukes Hospital “Price Checker” (Bethlehem, PA)

Sleep Medicine:

Direct Sleep MD (IL, AZ, WA, AL, and UT).

Surgery Centers:
Surgery Center of Oklahoma (Oklahoma City, OK)
Affordable Hernia Surgery (Rockville, MD)
Good Shepherd Health System (Ortho & Spine) (Longview, TX)
Nadora Healthcare (Johnstown, CO)
Monticello Community Surgery Center (Charlottesville, VA)
Movement Orthopaedic (Humble, TX)
Ocean Surgery Center (Torrance, CA)
Prairie SurgiCare (Peoria, IL)
Regency Health (New York NY)
Southwest Orthopedic Associates (Fort Worth, TX)
Texas Free Market Surgery (Austin, TX)
Pacific Surgical Center (Longview, WA)
Many listed as Kempton Premier Providers