So the domestic transfer window is still open till October 15th, meaning Liverpool could still sign players from the Championship.
Here are three goalkeepers just worth remembering -

Tim Krul - Norwich.
Market value - 3.6mil
Dutch international, would in theory have a good understanding with compatriot VVD.
Made some fantastic saves for Norwich last season & has plenty of experience.
At 32years old, the chance of a "big move" might be too tempting to say no.

Ben Foster - Watford
Market value - £1.08mil
England International. At 37 years old, Foster is in the twilight of his career, however his experience and reliability far outweighs any age concerns.
Qualifying as a homegrown player, he could easy slot into the squad.

Jack Butland - Stoke City
Market Value £5.85mil
At just 27, Butland has become the forgotten man of English football. Long time regarded as England's future no.1, making his international debut 8years ago! Jack's commitment to staying at Stoke has seen him fall off people's radar

The chance to play in both the Premier League and Champions League would fulfill many of Butland's ambitions, along with getting back in the thoughts of Gareth Southgate.
As being classed as homegrown, Jack slips into the squad without causing a dilemma for overseas player places