Manchester United are the reason why Chelsea are pricing Garnacho so low. Manchester United already made it public that they no longer need Garnacho, and they not going to work with him any longer, so that’s just the reason why Chelsea are pricing Garnacho so low, because Chelsea already knows that Manchester United won’t have choice than to sell Garnacho, because if they keep him, he won’t be playing for Manchester United, and United won’t have choice, they will keep on paying him, and Garnacho is rejecting other clubs offer, he really wants to play for Chelsea. So Chelsea believe they can’t spend huge amount of money on a player that Manchester United don’t even value.
Manchester united bought him for less than £1m and they're asking for £50m for someone they literally do not need, someone they have publicly announced for sales. Keeping him on the bench won't do anything good if we're being honest. Anything around £30-40m can be considered a good price.
He already made his choice to stay in England and to play for Chelsea, there's literally nothing Manutd can do right now than to accept what Chelsea is offering and maybe probably add sell-on clause to the deal.
Man United seems to still be waiting for offers from teams other than Chelsea, therefore, Man United still has not accepted the offer from Chelsea (Man United has set a price tag of £50 million, while Chelsea appears to be eyeing a deal closer to £35 million). I think Man United are in a bit of a predicament because if they delay too long, they might end up with a deal that doesn't live up to their expectations.
Especially if Garnacho doesn't end up leaving, I think it will be really detrimental, because it is clearly not profitable to wage players who no longer have the desire to play as he will only be permanent residents on the bench.