Usage: 4 forms in 10 verses
Form Translated As     In Verse(s)
αλλάγματι a price LXX.2Sam.24.24
barter LXX.1Kgs.10.28LXX.Lam.5.4
αλλάγματα prices LXX.Amos.5.12
άλλαγμα barter LXX.Job.28.17
bartered LXX.Lev.27.10
in barter LXX.1Kgs.21.2
its barter LXX.Lev.27.33
price LXX.Deut.23.18
άλλαγμά a barter LXX.Isa.43.3

Liddell-Scott-Jones

ἄλλαγμα (allagma) a price G:N-N

ἄλλαγμα-μα, ατος, τό,

that which is given or taken in exchange, καινῆς διαίτης[Refs 5th c.BC+]

__2 reward, price of a thing, [LXX+1st c.BC+]
__3 change, vicissitude, [LXX]

LSJ Scripture Refs: LXX.Deut.23.18