Help with a Data-Mining \ Clustering problem

[jsminer]

I am not sure which sub-forum to post on, so I posted here, too.
I apologize if this is not the correct place.

I am totally new to this data-mining business.
I would like for someone to point me in the right direction, plese. In my business - I will have a database with several tables (let's assume MS SQL Server). For the sake of example, I have a 'person' table and an 'purchases' table (each person can make several different purchases).

Here is an example of the 'person' table:

* ID
* First Name
* Last Name
* Address
*Date of Birth

Here is an example of the 'purchase' table:
* Date of Purchase
* Time of Purchase
* Store Location
* Number of Items Purchased
* Total Purchase Amount

What I would like to do is:
I would like to perform 'data-mining' in order to find out the "categories", or "clusters" of characteristics, that define each [b]'purchase amount'[/b].
Meaning - my target 'column' is the 'purchase amount' column.
Now I want to know all the different clusters of fields that produce each 'amount' in this column.

For example - I would like to know what is common for all the people who bought between 2,000$ and 2,500$ ?

Maybe they all came from the same neighbourhood ?
Maybe all of them were young & came from the same neighbourhood?
Maybe there are 2 distinct different groups that fit the '2000$-2500$' spending group ?

I am almost sure there are different categories (or distinct clusters) that match each price group...
one might be old people that come to buy at night,
another might be middle-aged people who buy more than 10 items,
and another might be middle-aged people who buy one Sundays.

From what I understand, this falls under the 'data-mining' region ([b]clustering maybe?[/b])

Is this true ? and if so, what are the tools I must use in order to find out these set of parameters that define the different groups for each pricing category?

Thank you very much !

John