New machine

Hi I've been sewing for a while and am debating investing into a higher quality machine at the moment I have a 6800c heavy duty singer and primary sew clothing. I want a straight, zigzag, overlock stitch and a button hole setting. Budget would be around 1000 because thats what higher quality machines seem to cost at the moment. I also want to look into learning how to repair my machine myself so I would want a machine that I can easily do maintenance on and want to know if anyone has advice on resources for that too. I am also debating purchasing an older machine but am worried about finding replacement parts. Does anyone have thoughts/recommendations?