Original cost or total cost?
Both my bumpers have been modified... the rear one extensively!
But...
ARB front bumper: $400 brand new direct from ARB (scratch and dent deal). Cost to date maybe $550 with new materials.
KMA rear bumper/tire carrier: $350 originally (IIRC), probably up to $1000 by now with new materials.
If I were to put a dollar value on my labor costs, there would probably be another $1000 in both bumpers. Then add the lights, winch, accessories, etc. for another $1500 or so.
That's $3K just in bumpers!