Our 4 bators haven't stopped going yet. They cool down only long enough to be cleaned, set back up and shipped eggs unpacked and put inside.
When you get eggs shipped during the hottest months I have found it better to put the eggs straight into the bator with the turner off for the first 24 hours. This keeps the, warm, but still to settle. If you leave them on the counter, they cool down from the heat of shipping. Now if the temps got high enough while they were in transit they could intact start to incubate in the shipping box. This is the reason to place directly into a pre-heated bator. This way you don't run the risk of cooling and thus killing the embryo development.
I hatch shipped eggs all of the time and have great hatch rates with the
Brinsea bators. Hoping to upgrade to a cabinet style next year.
You need to shop around for eggs, read up on breeds and figure out what you like. Non aggressive is too broad a want. Do you want brown, white, or colored eggs? Do you want large eggs or small eggs? How many can you keep if in city limits? Since you don't need a roo to get eggs, pick a breed or multiple breeds based on your climate and the birds ability to handle the extreme heat or cold and for the egg production and color you want.
If you have never hatched before, don't break the bank for a rare breed right off the bat.