What insurance are you under? Are you on Medicare yet? When looking at provider prices, the US is really weird, and no one knows how and why the crazy pricing system exists. The charge first requested by the provider is one thing, the price that Medicare or the insurance company accepts and pays is MUCH LESS, like even only 10% of the "full retail provider" charge. With Medicare your responsibility is based on the Medicare price not the price of the provider (of course it has to be a Medicare covered procedure). I would guess for younger people any copay is based on the insurance company terms.
BUT if you have NO insurance, your price is that crazy high price stated by the provider and then you have to negotiate with the provider for a lower price. That is why uninsured people went bankrupt over medical expenses.
For example, my recent colonoscopy done in Mayo hospital Rochester, had a charge of about $13,000.
Medicare approved amount was about $1600 and Medicare paid 80% of that amount. My Medigap insurance paid the remaining 20%, less than $300. I paid nothing,
I do not know what billing info you got but ask your insurance company if you are not on Medicare.
P.S. For older people they like to do colonoscopies in the hospital because of the higher risk.