Hi and welcome to the forum from a serial Coupe owner.
I'm assuming you are thinking of a 3.0Si - Ms have a few other things to allow for!
The N52 is a great engine but can suffer from oil leaks from the cam-cover and oil filter housing gaskets. Rear brake pipes can suffer from corrosion in front of the nearside rear wheel and tailgates have been known to corrode - just open it and look around the edges. The water pump is electric and will at some point die, but how long they last is a bit random. My first Coupe needed one at 60K but my second seemed to be on the original pump at 90K! The issue is when they do die the engine overheats in about a mile and new pumps cost £250 or so as long as you don't buy them from BMW who charge over £500 for them! Worth bearing in mind when you are looking as a car that has already had one gives peace of mind.
Only just over 2,000 Coupes were registered in the UK so if you are looking for specific colours or options it may take a while to find the right one. And there were 2 trim levels, SE and Sport. Sport had M-Sport suspension (lower and stiffer), steering wheel and crucially seats that tend to change hands for up to £1,000, although some SEs had them as an option.
Standard spec was pretty mean although they all had electric seats with driver's memory and headlight washers. But Bi-Xenons, rear parking sensors, heated seats, MFSW, cruise control and cup-holders were all options. Of those the last two are pretty simple to retro-fit.
Good luck finding the right one.
Although once you do you might want to change your user name to E86!