Most of us use the store as I'm hoping for some cleared up issues. I have listed here I believe everything you can get. Now I do know some of the answers to a few of these but I was hoping that someone can break it down item by item (for everyones sake) what each of these purchases does and if they work.

Bank
Give Gifts
Buy Lottery Ticket
Thief
Colored Username
Donate
Change Username
Bold Username
Glow Username
Colored User Title
Shadow Username
Bold User Title
Change Others Custom Avatar
Thief Immunity
Change Others User Title
Italic User Title
Underline Username
Italic Username
Buy Reputation Points
Remove Custom Avatar Immunity
Change Custom Avatar Immunity
Reputation Points Immunity
Remove Others Custom Avatar
Remove Default Avatar Immunity
Change Default Avatar Immunity
Underline User Title
Unlimited Reputation Per Day
Remove Others Reputation Points
Steal Others Reputation Points
Remove Others Default Avatar
Change Others Default Avatar

Okay. Leave it up to RP06.

Bank - That's to despoit your points to earn interest
Give Gifts - Give gifts to another forum member
Buy Lottery Ticket - buy a lottery ticket to win points
Thief - attempt to steal points from another forum member (Careful! The possibilities is low!)
Colored Username - Changes username text colour
Donate - donate points to another user
Change Username - That's to change your username
Bold Username - Make your username bold
Glow Username - Make your username glow with the colour provided
Colored User Title - change the user title colour
Shadow Username - drop a coloured shadow on your username
Bold User Title - make your user title bold
Change Others Custom Avatar - change other forum member's avatar
Thief Immunity - protect yourself against theft
Change Others User Title - change other forum member's user title
Italic User Title - make your user title italic
Underline Username - make your username underlined
Italic Username - make your username italic
Buy Reputation Points - This will allow you to increase your reputation in a devious way!
Remove Custom Avatar Immunity - Protects your avatar from others removing it
Change Custom Avatar Immunity - Protects your avatar from others changing it.
Reputation Points Immunity - This will allow you to receive immunity from others changing your reputation.
Remove Others Custom Avatar - Removes other person's avatar
Remove Default Avatar Immunity - This will allow you to receive immunity from others removing your custom avatar.
Change Default Avatar Immunity - This will allow you to receive immunity from others changing your default avatar
Underline User Title - Makes your user title underlined
Unlimited Reputation Per Day - This will allow you to give reputation as many times during a day as you want.
Remove Others Reputation Points - This will allow you to remove reputation points from another user!
Steal Others Reputation Points - This will allow you to steal reputation points from another user!
Remove Others Default Avatar - I don't know, but it says: This will allow you to receive immunity from others changing your default avatar (I think it may not be true)
Change Others Default Avatar - Change other people's default avatar

What would be useful beyond the descriptions is the knowledge of, if, any selected choice is worth it. The descriptions can be looked up easily but to a new member, like I once was, who saves up for something -any of these- would like to know more. Like does (fill in blank) work? How long does (fill in blank) last? Etc, etc.

Everything is set in stone and lasts forever except for the immunities and reputation points, those only last for 1 month. I believe if you change another members avatar it lasts for 1 week.

So basically everything is worth its price. The bank also distributes a 2% interest every two days.

So basically, everything is just for looks and customization. I changed my username color to black, and it's all I plan on doing. Changing your username, well, I agree with it to some extent, but I don't encourage people changing their names every couple of days or anything like that. If you are just looking to have fun, put your bux into the bank and get interest on them. Depending on the thread, I also wouldn't buy thread customizations because well, once the thread is answered or dies down, your bux basically went to waste. I guess that's really all I have to say, I'm not sure how else to put anything. If you want a colored username, just go ahead and get it, that seems to be one of the more popular ones along with actually changing your username.

So basically everything is worth its price.

Actually I personaly think thief immunity isn't because anyone who trys to steal points only loses them. :) Shame on them. :)

And thanks for adding some light to the question as well. :)

Also how does the buying repuation points works? Does it work?

Yes it does work :D