My Dad's funeral was about 4.5K last year.
Very simple but we did use an expensive firm because they are good and made everything easy (we've done a lot of death in the past few years).
We chose the cheapest coffin because it was the nicest (no bloody fake brass), cremation, hearse only, small chapel at the crem, live screening was included in the crem fee, humanist celebrant, newspaper announcements in two papers, 100 orders of service which I then posted out to people who hadn't been able to attend due to covid.
We paid for the flowers ourselves (about £100) as we wanted to use a specific off list florist.
The costs of the funeral ultimately come from the estate but the funeral directors are very keen to be paid up front. It's worth thinking about as not everyone has this kind of money to hand (I don't - most of my savings are tied in to get a better interest rate or held in an ISA).
I was lucky in that my overtime payment for all the additional work I had done during the first wave of the covid pandemic landed as the funeral directors bill arrived - as I didn't need the cash immediately I used that to pay for the funeral (my siblings were delighted!) I've only just been paid back as it took time to get all the money in from my Dad's accounts.
My suggestion to friends' parents is that they set up a joint account with one of their children to act as a funeral fund (as typically joint accounts aren't frozen post death and as a minimum the money contained within is felt to belong to the survivor 50:50). This obviously relies on a degree of trust between parents - child and siblings....
I'm the first of my friends to lose a parent (and have now lost both of them) and have actually written a letter to my friends' parents about things they could consider doing to make things easier when they do die. This might seem a bit odd - but death is the great certainty in life and most people don't want to make it harder for their survivors than necessary.
The difference in admin burden winding up my Mum's estate (crap financial record keeping resulting in having to contact masses of financial institutions to find out if she even had an account with them any longer) vs. my Dad's (one spreadsheet, kept in a place we knew about detailing all accounts held, updated when he closed one and opened another and containing rough balances was unbelievably helpful... he did forget to mention though that he still paid his credit card & other bills by cheque so we didn't pay a few things, assuming they were on direct debit so the estate incurred some late payment charges although most places did agree to refund them...)