Benjamin had been married before he was married to Sarah, and assumed to be a little older than Sarah, so guess born about 1736.
His first two children take the names of his parents:

Name:    Benjamin Buckley
Event Type:    Baptism
Baptism Date:    25 Dec 1734
Baptism Place:    Oldham, St Mary, Lancashire, England
Father:    James Buckley
Mother:    Sarah Buckley
Reference Number:    GB127.L185/1/2
Abode: Waterhead Miln

He was married to Hannah, and had children in 1754,56,58 so this baptism in 1734 is about right.

Name: Benjamin Buckley
Event Type: Burial
Burial Date: 28 Aug 1777
Parish: Saddleworth, St Chad
Parish as it Appears: Saddleworth
Reference Number: O9/1/1/5
Item Number: 6
Archive Roll: 905
Text reads: Benjamin Buckley Clo'r (i.e. Clother) of Shelderslow
(no age or wife recorded)

Hannah was from Coldhurst (as recorded on Bishop's transcripts for her Marriage to Benjamin).

Baptised: Oldham & Shaw, St. Mary
Hannah, daughter of Joshua Crosley of Coldhurst, weaver by Jane his wife.  24 January 1735

Name: Hannah Benjamin
Event Type: Burial
Burial Date: 23 Jun 1760
Parish: Oldham, St Mary
Parish as it Appears: Oldham
Spouse's Name: Benjamin Buckley
Reference Number: GB127.L185/1/4/1

Burial June 23 1760
Hannah Wife of Benjamin Buckley of Coldhurst high barn

Name: James Buckley
Event Type: Baptism
Baptism Date: 5 May 1754
Parish: Oldham, St Mary
Parish as it Appears: Oldham
Father's Name: Benjamin Buckley
Mother's name: Hannah Buckley
Reference Number: GB127.L185/1/3/1

James, son of Benjamin Buckley of New Earth Weaver by Hannah his wife

Name: Sarah Buckley
Event Type: Baptism
Baptism Date: 8 Feb 1756
Parish: Oldham, St Mary
Parish as it Appears: Oldham
Father's Name: Benjamin Buckley
Mother's name: Hannah Buckley
Reference Number: GB127.L185/1/3/1


Sarah, daughter of Benjamin Buckley of Newearth Weaver by Hannah his wife

Name: Sarah Buckley
Event Type: Burial
Burial Date: 7 Jul 1760
Parish: Oldham, St Mary
Parish as it Appears: Oldham
Father's Name: Benjamin Buckley
Reference Number: GB127.L185/1/4/1



Burial: 7 July 1760
Sarah a child of Benjamin Buckley of Coldhurst high barn

Name: Abraham Buckley
Event Type: Baptism
Baptism Date: 24 Feb 1758
Parish: Oldham, St Mary
Parish as it Appears: Oldham
Father's Name: Benjamin Buckley
Mother's name: Hannah Buckley
Reference Number: GB127.L185/1/3/1


Abraham, son of Benjamin Buckley of Coldhurst High Barn Weaver by Hannah his wife

Name    Abraham Buckley
Death Age    54
Birth Date    1759
Burial Date    29 Dec 1813
Burial Place    Shaw, Lancashire, England
Register Type    Bishop's Transcript
Reference Number    DRM 2/251/11

Name: Betty Buckley
Gender: Female 
Christening Date: 06 Jan 1760 
Christening Place: SAINT MARY,OLDHAM,LANCASHIRE
Father's Name: Benjamin Buckley 
Mother's Name: Hannah 
Indexing Project (Batch) Number: P00562-3 
System Origin: England-ODM 
GS Film number: 0093576-578, 0223739 

Name: Betty Backley (should be Buckley)
Event Type: Baptism
Baptism Date: 6 Jan 1760
Parish: Oldham, St Mary
Parish as it Appears: Oldham
Father's Name: Benjamin Backley
Mother's Name: Hannah Backley
Reference Number: GB127.L185/1/3/1

Betty Daughter of Benjamin Buckley of Coldhurst High Barn by Hannah his Wife (Oldham, 6 Jan 1760)