well, there is going to be a lot of mixed feelings on this one. I'm not sure if at Tractor supply you are looking at the little giant or the Hovabator. but in that price range I know it is a still air your looking at. I personally have mixed emotions on those two. I own and use both of them. I much prefer the construction of the Hovabator. it's a lot heavier and fits together quite tightly. The Little Giant looks like it will leak a lot and is not near as sturdy. The Hovabator comes with a liner for the bottom that the little giant lacks.
With all that said which probably dosen't mean a lot to you.
Both will work.
it is very very very important, especially in the little giant, that you group the eggs in the center of a still air. hatch times can vary due to inconsistant temps inside a still air without a fan to mix it up . So don;t get excited if some eggs don't hatch till day 23.
Your not running a turner, so do not dilly dally around when your turning your eggs. your letting the heat and humidity out.
A GOOD hygrometer is your best friend. I like the ones with the remote probe you can pick up for around 14 bucks online. Don't worry about keeping the humidity dead on 50% ( I actually let mine drop to about 10% before adding a glass of water every few days) and I don't close the vents.
The Hovabator with the "wafer thermostat" does maintain a steadier temp then the Little Giant does. and that caused me some real concern at first.. but. in the real world.. it just dosent make any difference at all that the Hovabator maintains 99.5-100.5F and dose not range much more then that at all when my Little Giant has been known to ride a 97F - 102F wave all day long and the hatch results are the same.
I hope I did not bore you.
I hope you find some of this reassuring
I hate I get long winded but if I cut my answers too short you may miss something that may save you some aggravation.
RULE 1 most failures come from being overly cautious.
RULE 2 failures will continue to be failures if your too scared to experiment.
And do not get discouraged if your hatch rate is between 30% and 60%
Adding a fan and a turner will kick it up in the 80% to 100%
You can add those things over a period of time if you get the " hatchin bug "