That"s the verdict of Spanish football expert Graham Hunter.
Barcelona are keen on both players as they hunt for Neymar"s replacement.
Liverpool have turned down two bids for Neymar, the last of which was worth £90m.
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They don"t want to sell, and Borussia Dortmund aren"t keen on losing Dembele either.
And Hunter thinks the Spanish club can only afford to sign one of the star players.
"It"s really important for everyone to know they don"t have it all (the Neymar cash),” he told Radio Five Live.
"First of all, when you balance your book, they"d spent in terms of bonuses, in terms of buying the player, in terms of legal fees well over €100m (£90m) securing Neymar over the four years.
"And that"s not the end of it.
"Barcelona are taxed on what they get from PSG, therefore to have anything near €100m (£90m) they must borrow more money if they want to buy either Dembele or Coutinho.
"I would say based on the briefings Barcelona have given me in recent months about the cost of renovations, they spent huge money on new contracts for (Luis) Suarez, (Lionel) Messi, (Sergio) Busquets, (Ivan) Rakitic and the goalkeeper (Marc-Andre) Ter Stegen.
"I do not believe they can afford Coutinho and Dembele.
"Dembele is very, very important. If they sign him and Liverpool say they don"t want to sell, I don"t think there"s the money at Barcelona to buy Coutinho too.”
Liverpool insist Coutinho is not for sale and they consider the case closed.
The club's owners FSG issued a statement this morning to firm up their stance.
"We wish to offer clarity as regards our position on a possible transfer of Philippe Coutinho," they wrote on the club's website.
"The club's definitive stance is that no offers for Philippe will be considered and he will remain a member of Liverpool Football Club when the summer (transfer) window closes."
Dortmund ace Dembele appears to have taken a different approach, though.
He went AWOL yesterday and was suspended and fined by the German club for not turning up at training.
Borussia are understood to have turned down an offer from Barcelona for the player.
The two clubs have held talks but the Spanish side"s bid doesn"t meet their valuation.
