I feel like I can contribute to this conversation! I just started my uking voyage around 9 months ago. Started not knowing what to buy and what I was doing, and got a cheap Alvarez soprano from eBay. Enjoyed it for a few months, felt that it was holding me back due to the smaller size and toyish sound.
I then found a Lanikai CKCGC concert on Craigslist for $140, seemed like a logical step up and enjoyed that for a good 6 months. Learned a lot of great songs, learned a great deal about fingerstyle and different string types and how they affect sound and feeling of the uke. Again, feeling like I was a bit limited by the size, but mostly that those I saw online shredding in the way I wanted to were playing on instruments very different from my own (solid body tenors from reputable brands, exclusively).
Just this week finally spoiled myself with a cedar top acacia body tenor deluxe Pono from HMS that I am absolutely loving.
I can say every step of the way I was in some way limited by what I was playing. But I don't think I really understood that until I made the next step upward.
Fortunately for us, the resale on mid to high end instruments is quite good. I could resell this Pono today and make 90% of what I spent on it back. Meanwhile, buy a new car, electronics or numerous other things and you lose 40% as soon as you buy it.
The Buddhist in me says be content with what you have, and learn skills necessary on more humble equipment. But we all know that when you have pride in what you have, that you spend more time with it and really enjoy the journey more. And we do only live once