I am in the market to buy a handgun for my home security. I am willing to spend up $300 on a hand gun. Now. I have check these boards and read some posts on what would be a good handgun. The usual brands came up: Beretta, S&W, Ruger, etc. One of the posts came to the conclusiong of getting a Ruger MKII . I may end up buying this brand. But. I noticed while checking several hand gun stores and googling, the mention of the Bersa Thunder 380 ACP. How good is this hand gun for a beginner hand gun owner and for home security? 
Wikipedia Article on Bersa Thunder 380
First question: why a handgun? 12 and 20 gauge shotguns suitable (indeed, superior to any handgun) for home defense can be had well within that price range. They require less training to use (you have received basic firearms handling training, right?) and are the most devistating firearms that can be readily purchased by a civilian.
The Bersa has a relatively good reputation for quality, and is built on the Walther PPK pattern, which is a venerable and respected design, but the .380 ACP is marginal for use against humans. You can probably find a good quality used .38Spl or .357Magnum revolver for under $300 with minimal searching, and a lot of used 9mmP and .45 ACP autos at or near that price.
The .22LR (as in the Mark II) is inadequate for any defensive use. It might serve in a pinch, but I wouldn’t buy any defensive firearm in that caliber. while the .22LR has been responsible for more deaths than any other caliber, the reliability of stopping an attacker quickly is very low. If you are concerned enough about being attacked to warrant purchasing a firearm, select a caliber that can effect the desired result with confidence. The .22LR just isn’t that.
Good luck to you with whatever you decide.
Stranger
A) No. I haven’t had hand gun training and will be looking for such here in my region.
B) I am not wedded to buying a hand gun. As a matter of fact, after discussing this with my brother, who is handgun owner, he also suggest that maybe I should also look into buying a 12 or 20 gauge shotgun.
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The OP is aiming for opinions, so let’s shoot this over to IMHO.
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Would a BERSA THUNDER 9MM COMPACT be better than it’s 380?? 
The 9mm is the smallest cartridge I would consider for pure defense use. I wouldn’t turn down a .380 if the alternative was beating them with a stick, but it wouldn’t be my first choice. A pump-action 12 gauge with an 18 inch barrel and full length magazine is what I consider to be ideal for a home defense gun.
What would you and posters recommend for such?
The Mossburg 500, Ithaca Model 37, Remington 870, and Winchester 1300 are all fine pump-action 12 gauge (some are also available in 20 gauge) shotguns with a variety of configuration options.
I don’t have any personal experience with it, but the Bersa Thunder 9mm looks fine and appears to have a good reputation for reliability and decent accuracy. I’d get the full-sized (for a house gun) rather than compact though; the more weight and longer sight range make for a more easily managed, accurate firearm. The latter may not be of such a concern at typical combat range (~21 feet and less) but the extra weight definitely reduces felt recoil. Unless you plan on carrying, though (or only have one hand) the shotgun is a better weapon.
Stranger
I second the Mossberg. Twin-rail pump…get it in 12 gauge. Load appropriate shot for your home situation. Look for a sale at a sporting good s store and try some out for size. Then get trained on it and put a couple hundred rounds through it. Once you are comfortable with it, and **every single person ** in your home is trained and comfortable as well, bring it into the house.