I work in Additive Manufacturing and 3D Printing.
The printers we use are not in the price range you stated. Those that money can buy cost several tens to few hundred thousand USD range.
We have many printers. Some have been around 15-20 years and others were manufactured less than a year ago that run much faster. We several different additive and 3D technologies with many materials, configurations, methods of part analysis, methods of build file preparation, methods of building, and methods of processing and finishing parts.
Our older machines still run beyond specifications provided by their manufacturers. Experienced people maintain them and keep them in an near-ideal environment. In every part of the process, experience with the machines and process is essential to producing quality parts. Most companies fail when they think that they can just "print parts" on their own. It doesn't work like that, even with some of the latest promises from machine manufacturers.
If you want to invest in the sector, and you can take on the risk, that is up to you. As a short-term investment it might or might not be a great investment, depending on news that comes up here and there that get people's attention. But, most in the sector believe that 3D printing and additive manufacturing will be transitioning from a historic phase of primarily producing prototypes and small batch parts into a production phase. That's not a forward looking statement for a single company or companies; it's a reality across the sector. Customers want that, and it will be provided.
Be aware, especially as an investor, that the reality of the market is not what you see:
Imagine all of the large companies that need to make parts and iterate on part designs quickly, some of which that could neither be machined nor made by hand. That's current reality.
Then imagine large companies that want printers constantly dedicated to making parts for them over and over, being able to iterate on design without stopping to change anything out. That's possible now, but many aren't doing it yet.
Now imagine most consumers expecting everything that they buy to be tailored specifically to their needs. Those products would have properties and behavior that would seems magical compared to today's. That's where we're headed within our lifetime.
>I see 3D printing services out there but can't understand who might be using them when you can buy printers for relatively little money.
My impression is that 3D printing is a hassle; between cleaning nozzles, babysitting things, polishing/sanding things post-print (removing supports, etc) and all the other work required.
I love that 3D printing is available, and I love that thingiverse and similar sites let you share models, but in the past year I've only wanted to have ~4 small enclosures printed for hardware projects. At that volume paying somebody else to print something for me is a much more effective use of money than buying a printer and managing it.
I wrote about this, briefly, here:
https://blog.steve.fi/3d_printing_is_cool.html
In short - 3d printing is cool, but its still not a "hit print and wait" process. Until it is I'd rather outsource the actual printing to people with more patience than I possess!