I have an STS one too and love it. Thick enough, comfy, and tiny when packed. I have the lightweight one in large, not the premium with the cover. I'll take it when traveling anywhere instead of gambling on what kind of pillows are at a hotel or mom's lol.
I do think they are overpriced for what it is. After a couple years I had problems with pinhole leaks for no apparent reason just suddenly developing. Contacted STS and they sent me a new one so good service there. I appreciated that they took care of me but if this one doesn't last longer I'll still be forced to conclude the payoff wasn't worth the money. I love the pillow but for a premium price I want a premium product that lasts a long time. Especially when a nice shredded foam Thermarest pillow that will last forever is cheaper.
So, while that pillow was getting replaced I needed one so I poked around and found a knockoff on Amazon. If you search they look almost like the STS ones, they are pretty much a blantant rip off, even the "aeros" name. But for $10 I figured why not. Pretty decent pillows, maybe 80-90% of the STS. Valve isn't as good and it's in a weird place on the side. Storage sack isn't as nice. For $10 I'd use it. Time will tell how it holds up, I've only had it couple months. It was perfectly fine for that 5 day trip then when the new STS came the kid wanted it so I passed it over to her. I think those are good place to start if you want to try the inflatable pillow thing without dropping $45. The STS is marginally better but not 4x's IMHO.