I think that the entry level ~$40.00 incubators are a good start to see if you really like hatching chicks. Of course, the more dollars you spend the more convenience and reliability you will get (same as with everything you buy). I would say that all of of the sub-$100.00 incubators that one can buy are pretty much equivalent in terms of quality.
However, you could make your own incubator for much less than $100.00 and still have the reliability and options of some of the more expensive models. It all depends on how much ingenuity and time you have to dedicate to building one. Many people on this forum have successfully engineered and built their own incubators from recycled spare parts around their homes or from purchased pieces and parts. For many, building the incubator is part of the hatching experience and a wonderful do-it-yourself project that brings great satisfaction when that first chick hatches.
I started with the Little Giant 9200 still air which I upgraded to forced air by installing a recycled computer fan. However, the power adapter for the fan I built costs me about $18.00. So I might have saved about $10.00 plus some shipping over buying the higher end forced air Little Giant model. I didn't feel like waiting for mail order or building my own incubator, but purchased my first one locally so I could get started hatching eggs right away (convenience factor and my lack of patience in this instance).
Emboldened by my hatching success the first time around, I bought a second incubator, the Hovabator Genesis Model 1588. This one is quite the cadillac of styrofoam incubators with a preset thermostat. With the automatic turner, it's pretty much plug and play, add water, pace back and forth, and wait for the chicks to hatch. So far the 1588 has been an easy incubator and I think if the electronics hold up and I am careful to keep it cleaned, it should perform reliably for many hatches to come. I'm not planning to hatch hundreds of birds at once or get into maintaining or breeding large numbers of birds, so I think I will be set for a while with my two incubators.
So build your own, buy low end to get started, or spend hundreds for a high end, state-of-the-art marvel of engineering. It's all a very personal choice only bounded by your time, energy, and depth of pocket book.
I would agree with what Pinelady said about much of the incubation success depending on egg fertility and quality. Without good eggs you could use the most wonderful incubator in the world and still end up with rotten, scrambled eggs. Good luck in deciding on the right incubator for you.