If you stick with A class AMG alloys, you should be all good with the offset and, clearances of calipers etc etc. The only thing you are going to need is deep pockets. New 4 AMG alloys can cost around £2k-2.5k without tyres and, you are going to need those as the AMG alloys are all 17, 18 or 19" rims.
It will though change the look of the car for you and, from time to time, they go on sale on here at decent non new prices. Also consider aftermarket brands. You will get the look at bargain prices. Bear in mind that if you go aftermarket, you should advise your insurers. You can chose not to but, it could affect a payout if you have an accident. Sticking with MB rims, is a cosmetic change and, whilst you could still notify your insurer, the fact the wheel is designed for the car wont affect payouts.
I am looking to sell a set of mint 18" amg alloys off of my a45. I am looking to go multi spoke in black as I want to stealth the car.
Open to sensible (not silly) offers. All tyres included and plenty meat.