As a doctor, I agree this is stupid and painful. It's mostly due to hospitals / group practices haggling with insurance companies like some bazaar. Unfortunately, since you have UC and the procedure is a bit more involved than standard screenings, it doesn't qualify as a screening colonoscopy. They are required, however, to provide clear pricing:
https://www.cms.gov/hospital-price-transparency . I would get quotes from multiple clinics.
If it helps, the codes to ask for prices are (keep in mind they should only code one procedure):
45378 – Colonoscopy, flexible; diagnostic, including collection of specimen(s) by brushing or washing, when performed (separate procedure)
45380 – Colonoscopy, flexible; with biopsy, single or multiple
45381 – Colonoscopy, flexible; with directed submucosal injection(s), any substance
45382 – Colonoscopy, flexible; with control of bleeding, any method
45384 – Colonoscopy, flexible; with removal of tumor(s), polyp(s), or other lesion(s) by hot biopsy forceps
45385 – Colonoscopy, flexible; with removal of tumor(s), polyp(s), or other lesion(s) by snare technique
45388 – Colonoscopy, flexible; with ablation of tumor(s), polyp(s), or other lesion(s) (includes pre- and post-dilation and guide wire passage, when performed)
45390 – Colonoscopy, flexible; with endoscopic mucosal resection
Hope this helps, sorry this system is so dumb.