Hi and welcome to JA, I'm Billy and will help you with this the best i can.
As for any used car, maintenance cost will vary greatly according to the vehicle's condition.
Nonetheless, as you seem avid to really maintain the car at good condition, this will save you a lot (preemptive maintenance).
I suggest you get a service manual for this car, and maintain it well, if you DIY the maintenance it would cost you around 300$ a month, now that's a rough estimation depending on car condition, how much and HOW the car is driven.
The per month estimation i gave could vary from month to month, but i think it would average the prior listed number.
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