The job market, and qualifications required to practice, vary widely by state. Make sure to research your specific region, and don't trust what the schools are telling you. There are a lot of quasi-scammy for-profit medical assistant schools out there.

This is OP: thank you for this advice! Are there a decent number of jobs out there?

The education is approximately two years. You can go through a community college program or some hospitals have there own radiology schools. Most medical imaging technicians become xray tech's first. You have to get registered and there is a state license. After you've work a little, you may be able to cross train in other areas (CT, MRI, ultrasound, etc.). Some of these have there own registry. The specialty areas pay more than xray tech's, which start around here at $18 - $20 per hour.

What's the education requirement for getting qualifications to be an ultrasound tech?

Are there part-time jobs available in the field (esp. for someone new to the field), and what do they pay?

For someone who knows the field well, what is the quality of life for someone who does this for a living?

I'm looking to start a new career, am very much a people person and interested in medicine and science but don't have the stamina/money/time to pursue a medical degree.