if you're willing, the following macro will reformat your worksheet so that it can work with a standard mailmerge:
Code:
Sub ReformatData()
Application.ScreenUpdating = False
Dim r As Long
With ActiveSheet
.Columns("A:H").Copy
.Paste Destination:=.Range("I1")
.Range("I2:P2").Delete Shift:=xlUp
For r = .UsedRange.Cells.SpecialCells(xlCellTypeLastCell).Row To 3 Step -2
.Rows(r).EntireRow.Delete
Next
End With
Application.ScreenUpdating = True
End Sub
After the macro has been run, you'll see that every second row has been moved to columns I:P.
So that the mailmerge can access the data correctly, all you'll need to do is to rename the column headers so they correctly differentiate buyers from sellers.