Should I buy a Plot ? Apartment ? Villa ?

Well first of all, are you a local or an expat?   the difference is that as a local, you can buy everywhere in Bahrain whereas as an expat you can't.

Similarly, as an expat, I would advise you to buy for the sake of rental return as most people wouldn't be retiring in the middle east after their jobs finish.  So return and property value appreciation is what they need; not safety and security of a home.  This means that for this category, it's next to useless to buy a plot.  Why waste time and money building a house if you and your children are not likely to live in it for ages.  Unless of course you are one of the few who stay for decades.

Check out bahrain property world on the internet.  And from what I can see, apartments are available for your listed range.  Villas might be too but not in the good areas.  The thing about property is very simple : location, location and location so I would suggest that you pick the right location.  Buying property anywhere is not really advised if you want to make money out of your investment