One way would be ifelse
:
colorBar_YaxisValue = 10
f = Figure(resolution = (1000, 800))
ax = Axis(f[1, 1], title = "test", ylabel = "Prices")
barplot!(ax, 1:20, 101:120,
color = ifelse.(1:20 .== colorBar_YaxisValue, :red, :blue),
direction = :x)
f