I currently have Vredestein Ultrac Sessantas which the last owner fitted (one month before I bought the car). I am actually very impressed with them and they were apparently about £500 for all four (19" wheels). I will probably try Michelin PS2/3s next time I need to replace all four, but would happily fit Vredesteins again.
I've had it since July last year. It's covered nearly 8,000 miles since then. No problems with it whatsoever. The wheels needed refurbishing when I bought it and it needed a new fog light (both taken into account in my purchase price) - both issues I have rectified.
They are strong cars and generally don't have many issues. I think the most common recurring issues is snapping rear coil spring which are around £200 for a new pair.
I think servicing intervals are approximately 15,000 miles (they are variable based on how you drive). They follow a pattern of Oil-Insp1-Oil-Insp2. Oil services are around £150, Insp1 around £550, Insp2 around £800. £800 sounds hugely expensive, but do remember that it will only need to be done every 60,000 miles.
No problems getting insurance quotes, but I did pay around £950 last year (might get that down to £900 this year). Mid 20s, 3yrs ncb, no claims, no points.
My list was:
Must have/be:
Black or Silver Grey paint
16:9 Navigation
SMG gearbox
Red/Orange/Lime green/Cream leather interior
Harmon Kardon
Should have/be:
Sunroof if coupe
Facelift (LED rear lights)
19" alloys
Under £14,000
Under 60,000 miles
Can be:
Coupe
Cabrio
In the end I got mine for £14,950, but it came with a few bonuses including 9 months of BMW warranty, 4 new tyres and a recent service. SMG was a must for me, but is a much disputed topic.