Bennelli shotguns ('round these parts) are typically $700 and up; They now have a "budget" line starting around $400.
Remington 870's run $400 or more, Mossberg 500's start around $240.
Maverick is a Mossberg "budget" line. Their "Defender" model is a pistol-gripped pump-action with a 20" barrel in 12 Gauge, and retails for less than $200.
Norinco is now making a copy of the Remington 870 (but parts are not interchangeable) with "ghost ring" sights and 20" barrel. Retail price is well under $200! Norinco is a Chinese import; the quality of their products range from Fair to Very Good. Personally, I have a problem with purchasing products from a wholly-owned subsidiery of the Army of the Peoples Republic of China - the same folks responsable for the Tienemen Square Massacre. Please keep that in mind if you're looking to save a few dollars.
For the un-initiated, "ghost ring" sights are a desireable feature on tactical shotguns. The front sight is usually a heavy blade type, and the rear sight is a large ring. There are usually thick ears protecting both sights from impact damage. "Ghost ring" sight allow for rapid target aquisition, especially under low light and/or high stress conditions. They are ideal for shotgun use, where "close enough" usually gets the job done . . .
The natural progression of sight / target aquisition is: Rear sight, front sight (bringing the weapon into alignment), target. The ring makes it easier to aquire and align the front sight, and as your focal point of vision moves to aquire the target, the rear sight (no longer in sharp focus, and having served it's initial purpose) fades, or "ghosts" from view.
The only negative aspect (IMHO) of using a shotgun for defense is that if an assailant can get close enough to grab the muzzle or barrel, they can use superior leverage to effectively gain control of the firearm, i.e.: Where the business end is pointed. This is A Bad Thing (tm). That is why you do not try to find an intruder . . .
Home and/or Personal Defense is a "package" concept - A mindset that requires situational awareness and planning. As
Bozo pointed out, in many cases, your best "first line of defense" is a barking dog. Study the floor plan of your home, and decide where the most easily defensible (and "family-accessible"

room is. Equip it with a solid-core or metal door with a one-way deadbolt. Put a phone there, keeping in mind that you can't cut the line to a cell phone. Take a "defense course" and become knowledgable about current laws for your state, especially regarding the use of lethal force.
Your priorities are: Get the family to a safe area. Call for help; Tell them where you are in the house and stay on the line. Let the intruder know you are armed, and fully prepared to defend yourself. Wait for help.
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Tom:
I dropped my FFL as a gunsmith 5 years ago. I've performed onsite repairs on NFA firearms while I had it. Two calls to "local" NFA dealers yesterday confirmed
Bozo's experiences. Average wait for approval is 4-5 months with CLEO approval; suppressors included. And you don't need to be "a senator's son", or know one. Perhaps your experience has much to do with your particular area.
BTW, the M-2 Browning .50 cal is absolutely THE most impressive weapon I've ever had the priveledge to fire, followed by the MG-42.