Nice one mate - those 4.0L V8'S sound fantastic and they rev for days, but the size of your maintenance list is the main reason why i bought the Lexus IS-F over an E92 M3, AMG C63 or the RS4. This one looks to be very clean and well loved.
I decided to give up that pedigree and manual trans for peace of mind from a reliability point of view. Another big factor for me is that 99% of M3's are 2 door which would not suit me (car needs to be practical so my daughter can ride in the back).
Thankfully in my case with the IS-F the resist to modify is largely due to not many options, and what is available is stupidly expensive. I've only done exhaust, intake and a remap (currently 265kw atw with those mods - stock is 230-235KW atw).
Is the M3 black or that very very dark blue like they had in the E46? It's a bit hard to tell due to the overcast day when you took the photos.