The plastic trim around the steering wheel can easily be refurbished in high gloss black and it will bring extra value to the part. I've sold excatly the same steering wheel with refurbished trims for around £250 couple months ago.
The black trim in perfect condition is worth around £250 as well and the cost of a bodyshop painting the dash in piano black is around £80.
ps. The air bag will fit straight into your new m sport steering wheel and is literally a 5 minute job to swap it across but just to be safe make sure you discount the battery for 10 minutes before removing the airbag from your car.