well, as far as the easiest most simple handguns out there are revolvers. there are no slides or complicated moving parts, just a trigger and hammer. The smith & wesson 600 series(637,642, ect) are amazing little guns, they are built on a lightweight frame and capable of shooting .38 and .38+P(the round you want for defence) also the taurus judge actually is a great home defence gun, the 3" barrel model has an 18 inch spread at 20 feet with a No. 6 shot which is bout perfect for in home and there are a few companies really jumping on the bandwagon making 00 buckshot for the .410 now(3 9mm balls coming out at once).
Or if you like autos, Glocks are one of the most easy to use, reliable auto handguns out there. They come in every common handgun caliber(9mm, .40, .45, 10mm, .357sig, .50GI) As for safety on the glocks, it is all internal and on the trigger itself, when you look at them it looks like they have a double trigger(one inside the other) and until the trigger is completely dpressed that gun cannot fire no matter what you do. Also their barrels have whats called hexogonal rifling meaning that the shape of the barrel(hexogon) spirals and gives the rifling action to the bullet, this helps very much with their accuracy.
The S&W's mentioned above run $480-575 depending on where you are at
The taurus judge run $400-550 depending on if you get the 3" or 6" barrel, and if you get blued(black metel) or stainless steel.
Glocks range from 500 on up depending on which of the infinate number of extras you got on it lol but can pick up a standard model from 500-600