Why can't you take your car to an indy?
You never said why before.
I will save you some money for sure.
BMW and for that matter Toyota's too have water pumps that last around 50-90K miles.
The new electric ones seem to run the variable miles depending on conditions since some have reported corrison on the electrical terminals and cracks on the phenolic housing the pump runs in.
Others get significant miles out of them, just can't tell.
4 cylinder BMW mechanical water pumps on 318's almost never fail below 150K miles.
Strong suggestion is to find a good BMW indy and establish a relationship since you are not a DIY person.
Remember this is a forum where people come to learn and primarily try to get solutions to problems and some also piss and moan about issues. This isn't the norm for BMW or years ago they would have been out of business. I have owned well over 20 BMWs and have exactly one, repeat one water pump fail. That was in a highly modified non stock SC 325 that regularly had diet of 7000 rpms. When it did fail I knew it, flat bed to my garage replaced the pump out of service about 2 days cost was 40 bucks.
Think BMWs don't last?
My last BMW I sold is running just fine at 284K miles and this is an E36 M3 original engine.
Good luck with whatever solution you come up with and please post the outcome so we can all learn how this goes for you.
420-550 bucks depending where you buy it is pretty expensive for a waterpump but consider this the engine needs the most cooling when car is in stop and go traffic where a mechanical pump can't deliever it. I can see why BMW did this and it is going to be showing up in other manufactures also in the future...