When I was in the Army I was issued an IBA and then they came out with the kit that upgraded it with all kinds of accessory kevlar panels to afford greater side and bicep protection. The IBA is good and if you can find one cheap go ahead and get it. You can periodically find "pieces" of up-armor kits (i.e. a groin protector or a deltoid protector or a neck yoke) that still contain kevlar and are usually unused. You can cannibalize these parts to freshen up the kevlar inserts of your used, worn IBA you got cheap from e-Bay, AR15.com, etc.
A key ingredient to any body armor, however, is a rifle plate. Soft body armor (kevlar) is good for fragments and low-velocity pistol ammunition. When paired with a rifle plate it is fantastic. When standing alone... it leaves
much to be desired. Kevlar breaks down over time with use, exposure to sunlight and extreme temperatures. It is not unheard of for a soft body armor vest to be defeated by standard FMJ 9mm even though it may be "rated" to stop it, due to the vest being worn daily for a year or two in high heat.
If your life is worth protecting then it is worth protecting
well. Acknowledging the chance that you may encounter gunfire is a good first step but taking it the next step further and emplacing rifle plates (titanium, ceramic, steel, et al.) is how you elevate your precaution to it's next logical level. If you are in a situation where body armor is prudent then you will likely need to stop rifle or shotgun fire, since that's the preferred weapon of people that go into a situation where they
expect to use a gun, whereas handguns are what people take with them when it is
possible to use a gun.
All the above is a preface to me showing off my armor, anyways.
For my wife, she has a Desert Camo XL-IBA with two brand new XL-ESAPI plates. I added a few panels of extra, new Kevlar that I cannibalized from assorted up-armor parts kits like I explained above. The vest is XL but she isn't XL. This vest is loose on her but will have to fit the bill until I can acquire one in her size. I will eventually add two M-16 magazine pouches to the front and two 1-quart canteens to the rear. She is getting an SBR AR-15 in the coming months so this combination suits her needs for "last line home defense" should Hurricane Hugo's grandson show up and destroy civilization for another consecutive month or two.
For myself, I have an ACU XXL-IOTV with both deltoid (upper arm) protectors, neck yoke protector, groin protector, ass protector, and both side protectors installed. I have full-torso-wrap Kevlar protection. For plates, I have front and rear brand new XL-ESAPI and two used MEDIUM-SAPI installed in the side protectors. I figured a little extra plate protection on the sides would be a good thing to have should I need to keep my house safe from land pirates during times of "extra-legal civil strife." The sonofabitch weighs 40+ lbs naked, without any magazines or water. I'm not having to ruckmarch anywhere and, instead, am going to be fighting a defensive battle from behind cover. Since I am not abandoning my family, I don't need maximum mobility. I need maximum ballistic protection. I feel I have it.
And, just in case you're wondering what a little lady looks like wearing body armor, here's my wife showing off my IOTV with all four plates installed. That smile of hers quickly turned into a grimace due to the weight. It made her appreciate her "light" IBA, though!