Martin O'Neill is understood to be an admirer of Matthew Upson but has been put off making a formal bid for the 30-year-old by an asking price of around £12million.
He is, however, reported to have bid for Upson's West Ham team-mate Collins, who has held talks with Stoke over the last couple of days.
Portsmouth defender Distin would also cost around the £5million mark, but O'Neill is reluctant to pay over the odds for the 31-year-old having already had two bids rejected for the former Manchester City player.
The Villa boss is desperate to bring in proven quality at the heart of his back four to supplement Carlos Cuellar and Curtis Davies.
The retirement of Martin Laursen and the sale of Zat Knight to Bolton for £3million has left him short in that department.
Stephen Warnock has also been tracked for several months with Villa already having had one bid turned down for the Blackburn full-back.
He is keeping his fingers crossed that Rovers boss Sam Allardyce may make Warnock available after signing Real Madrid defender Michel Salgado.
In the midfield department, Tottenham's Jermaine Jenas is a player O'Neill is still keen on although his interest in his club-mate David Bentley appears to have cooled.