I've been looking at multiple lists of top 20 centre backs. Basically, no matter the publication Gabriel and Saliba are always in the top 5 with Rudiger and VVD.
It would need to be an offer of an eye-watering amount for us to even consider this, e.g., 120m+ pounds. The most expensive defenders historically (Gvardiol, De Ligt, Maguire), are all clustered around 80m pounds, and Gabi is universally considered above all of them.

Can we offer them Havertz instead at half the fee?

His deals up in 2 years. We need to get a new deal signed or talk of selling him has to be taken seriously. He's 27, if we could get him to sign a new 4-5 year deal we'd be able to keep him for the next 2 years at least and that'd be right through his peak. He'd still be able to go earn in Saudi then, they'll keep throwing money at players at least until 2034.

Selling Gabriel would be the end of the project.

I just don't think selling Gabriel makes sense at any price - even fees as high as 100m-120m, which would be a record fee for a defender. There aren't many like-for-like defenders at his level that are ready to step in and his chemistry and continuity with Saliba is one of the few areas of consistency we have had since Saliba's injury in the 22/23 run-in. If there was even a 90% replacement we could sign, I would consider it but I just don't see that defender out there that provides the requisite physicality, ball playing and leadership we need that isn't a project right now.

Just go and grab someone like Diomande. Young and has the physical attributes, defends well one v one, and with good passing. This is a business decision, and a no brainer at that in my opinion. Over 100 mill for a center back? Again, this isn't like a center forward or top class creative midfielder. Gabriel and Saliba are top class, one of the best pairings in Europe, but at the same time we defend as a team, we can and will cope.

So I say every player has a price but having looked at top defenders again, Saliba and Gabriel are soooo risky to sell. Amongst the top 10 or so defenders in the world, maybe only Bastoni from Inter could be gettable. So it’s extremely difficult. My big belief is always be improving. We could sell most of our fullbacks, Trossard, even Havertz and Martinelli in a pinch.
But right now the CBs, Saka, Rice, Ode feel untouchable

flobaba Liverpool bought van Dijk for £75m seven years ago, and I'd argue 75m then gives you more than 100m now. Point being, whether you're selling or buying a player you're facing the same choice - is the player worth more than that money?

I don't think any Liverpool fans regret choosing van Dijk over that amount of money, and for me Gabriel is in that tier or defenders.

QuincyAbeyie you should go back and look at comments from all the English media and pundits. They thought Pool were having a laugh.
The top 2 or 3 players in position, you pay anything for. It’s why City are giving Haaland £500k a week. He’s scoring at a rate Henry and Shearer could only dream off. Lock them motherfuckers down.

I love a lot of players on this team like White, Havertz, Martinelli but I’d be ready to sell them to fund an Isak. Selling a top 5 player in his position will lead to lots of sobbing yourself to sleep

Liverpool were able to buy both VVD and Allison because they sold Coutinho for so much money. He had been their best player the prior two years. So let's say for sake of argument that we get 150M for Gabriel, which we put together with the 150M we had budgeted, and now we recruit Isak, Wirtz, and Williams. Is that worth it? I don't know whether it is - but I do know there's always a number.

Exactly. Fork in big money from asset sale, use that to
replace outgoing asset and potentially supplement other areas. We don't have to be the best defense in the league to win the league. We need to get more points on board, and goal scoring / creativity is and has been our main pain point, not defending. We wouldn't need to be so dependent on Gabby's set piece prowess for instance if we had say Wirtz and Isak. We lose a big part, but potentially, holistically stand to gain a lot a lot more if we play our cards right. That's Berta's entire job isn't it?

QuincyAbeyie so may be 100m isn't the number. I'm not fussing over the details. 150 mill? 200m? Whatever it is that leaves us with more money than we would know what to do with. And then let Berta bring balance back to the force.

But every player is fungible, in my opinion

This is a hot take but I actually think that Saliba is more replaceable than Gabriel in our current team. There are other young ball playing CB's that are plus defenders out there who I would feel more comfortable partnering with a physical leader like Gabriel than vice versa. For example, I think if we sold Saliba and replaced him with someone like Huijsen, we'd be losing far less than replacing Gabriel with anyone out there right now. The only left footed CB in his age profile that could feasibly step in to his spot is Bastoni, as @Claudius said but I think he would get a lot more exposed in the EPL than he does currently in Serie A. And he's nowhere near the physical defender that Gabriel is.

samthegooner agree
One other thing to note is the way we beat Chelsea on the weekend. I know a lot of people were frustrated by that game but I watched it again. We exerted control throughout. And most of our control comes from the back. It’s the goalie and the 2 CBs especially . This defense is what makes us exemplary. You do NOT blow that up.

If you want to take risks, feel free to blow up the entire frontline except Saka. We have degrees of freedom elsewhere.

I'm just glad Gabriel, my G, is finally getting the recognition he deserves.