Might want to start with a handgun or shotgun.
I would not say that an AR-15, for example, is the ideal weapon for home defense. You’ll want training with any weapon you get, range time, and how to strip and clean it.
AR-15’s have a fairly involved field strip process, ammo is not easy to come by right now, and neither are the rifles for that matter. Also, none of it is cheap at this time.
Also, rifles have the ability to pierce walls when fired.
My two choice weapons for home defense are my Sprinfield Arms XD .40 cal pistol and my Remington 870 tactical shotgun. Both cost 500$ each for the base weapon.
Re: AR-15’s have a fairly involved field strip process,
Really?
http://www.youtube.com/watch?v=61WKv720_Ow
Oh, I have a Mossberg 500 and a .327 magnum revolver for the home (for the wife). I’m thinking down the road here (and monitoring the news...and remembering history). I do not have an arsenal. I do not have the money to begin amassing one now. But I am willing to secure a must-have piece of family protection for when things deteriorate.
I monitor the gun threads on FR. I love reading what those with much more knowledge in this area than I have to say. I trust my FR brethren in this area and trust them to be [more] ready [than I] but I assume I will not be able to secure an invitation to stay in their basement, help out with an occasional an shot-gun blast, tend to the wounded, etc. when you know what hits the fan.