I can only go by my own experience as this is my first BMW.
In April 2019, I bought an E93 325D Convertible. This is the folding hard top version and is the Sport Edition. Year is late 2012 and I bought privately for a little over £10K.
I was made aware by the seller it was due a service and it had done just under 65K miles. The bodywork was, and still is, immaculate.
Service revealed two rear tyres needed because of cuts on the inside sidewalls and a front shock absorber leaking. Apart from that, only oil and filters.
I guess that's the price of buying privately where you can't put it on a ramp and have a good look underneath.
I guess I spent £500 or so getting it legal and safe.
Since then, its done about 5K miles per year and is an absolute joy to drive. With the turbo diesel straight 6 engine there's plenty of power for my needs and even with runflat tyres, most of the time it's a comfortable ride.
I intend to keep it until I can't get in and out of it which I think was the previous owners problem. He was in his mid 70's and I'm still only just over my mid 60's !!
I have the oil and filters changed every year and this and any other required work, (not much) is done by a local Independent who is ex BMW.
Hope this helps.
When you buy, enjoy 🙂