What budget should I plan for if I want a machine I will not outgrow quickly?

The consensus across mainstream tech press and specialist communities is that around $700–$1,000 buys a credible long-term prosumer setup (Barista Pro, Barista Express Impress, Barista Touch). Stepping up to roughly $1,700 for a true dual-boiler package buys steam performance and temperature stability that most reviewers describe as near-commercial.