It's similar to buying a car. Some people have 3-car garages which hold a Beamer, a Mercedes, and the family SUV. Others are brand conscious and only buy Honda or Toyota. Others still are happy with the Ford they've been driving for 15 years. It depends on the budget, the features that are important, and the willingness to make the purchase. My DH asked me once (many years ago) "just how many sewing machines does a woman NEED in her lifetime?" THAT (as he found out) was the wrong thing to ask, as I countered with "How many power tools does a man NEED in his lifetime?"
For me it is simple: I research and test drive. Then I set a competitive price and I deal until I find the price I am willing to pay. My latest acquisition is the Baby Lock Crescendo which has a LASER LIGHT SHOOTING OUT OF THE NEEDLE. I mean, seriously, has the sewing world gone ka-rayzeee? I just HAD to have that machine. (Besides, it has all the other features I consider essential.) It took a while but I found my price and I am happy as a clam.
That said, there is no bill that isn't getting paid because of the expense. There is nobody getting deprived because I splurged. It was not an impulse buy and I plan to use her for a long long time. We do not have children so we get to play. Me in the sewing room and DH with the telescopes. Life is good.
To the person who is looking to get the Sweet 16: You may want to look at the Baby Lock Tiara which is the same model as the Sweet 16 but the table height has been adjusted to be flush with the machine base.