If you're going to be sewing on heavy materials, I would shoot for a Heavy Duty Singer or equivalent. Metal frame, piercing power, ability to handle multiple thick layers. There have been a few models out geared towards cosplay/couture that have the aforementioned traits in addition to no "speed limit".
Quality clothes can be accomplished by hand, they just require quality fabric and a lot of time/skill. How you wash, maintain, and store your clothing also affects its lifespan.
Sewing machines are sold anywhere you find craft supplies/yardage.