Learn to do simple tune ups and repairs by yourself
I would go even further to say ; Do everything yourself!
I have a friend of mine that literaly hates taking his car to a rapairman and repairs everything alone.
Though in this case the bike you got was in bad condition to start with ,if you want anything of good quality you must forget the cost and get some knowledge ,because good quality means knowing how to distinguish between parts that are better and worse. I have a bike with Shimano cassette that is a cheap one ,but is now 13 years old and runs on it.I bought a new bike a month ago and i am feeling the need to change the bearings on the pedals movement, but i will just wait the warranty man to do this if anything goes for now.Another example is the city bike i used before that one .. It was a russian 30+ year old bike and nothing except the brake cables needed replacing.So the word '' quality" is a very miscelaneous thing.
Another advice though would be - go simple and get a single speed bike with internal brake . If good quality you will not do any repairs on it soon.