'How much does a DBA earn ?' is always an interesting question !!!

A DBA is responsible for maintaining Databases within an organisation, so it is a very difficult and demanding job.
Therefore, of course, it is also a rewarding job, both financially and in terms of job satisfaction.

I have many years experience of working as a DBA, maintaining Production Databases in Investment Banks, such as J.P.Morgan and Salomon Smith Barney.
Those were some of the most demanding and high-pressure years in my professional career.

Here's a typical Help Wanted Ad to give you a feeling for the skills required -
"PL/SQL Developer With DBA Skills"
Multinational Multimedia organisation requires an experienced PL/SQL Developer who also has had DBA exposure,
with good Unix Shell Scripting skills.
Working on a systems migration project, you will have proven technical ability and excellent interpersonal skills.
An ability to be able to write PL/SQL packages & procedures, create database load scripts and set-up development databases is essential.
The position will demand some DBA support (approximately 20% of the role) however the support
will be of a wholly ad-hoc nature.
Working within an Oracle 7, 8 & 8i environment, associated experience is essential, as is solid commercial experience with PL/SQL.

PL/SQL is Oracle's proprietary extension to SQL,(PL stands for Programming Language
or Procedural Language).

You certainly need to know SQL, and learning PL/SQL will teach you SQL, but
you could learn 'vanilla SQL' first.
Check out this page for 'Online Training' which includes some SQL Tutorials ... http://www.databaseanswers.com/links.htm DBA Training Courses

DBA courses given by the Oracle Corporation are rather expensive.
Cheaper alternatives may be available from other training organizations, but 
if they are not Oracle Education partners you may be taking a risk.
Alternatives are available online from a variety of sources.
Check out this page for some suggestions 
in Oracle training.
Oracle Certification
The cheapest and quickest way to get Oracle Certification is to take a 4-day Course 
in Internet Database Operator. 
This costs substantially less than full DBA training but would give you basic skills and 
confirmation that you would like DBA work. 
Also you should consider signing up as an Oracle Partner. 
It costs about the same as a 5-day course, but includes 5 days free training (so it pays for itself),and 
subsequently you get 25% discount off training.
As I note on the http://www.databaseanswers.com/what_is_a_dba.htm page, Oracle is continually providing 
more point-and-click facilities for DBA work, 
so what you learn now for DBA work may become a legacy skill in six months time.
In practice, new versions of Oracle,(they are now selling 9i), will take some time to filter into the 
marketplace so 8 and 8i skills will still be in demand for a while.
Two other career choices I would recommend for consideration are System Architect using Oracle Designer, 
which would leverage an Infrastructure background, and Database Analyst, using Oracle's PL/SQL. 
This would involve much more hands-on work than the Architect role. 
The choice therefore depends largely on your preferences and how easily you can define 'job satisfaction' 
and translate that to one of a number of clearly-defined job profiles or roles in the marketplace.
About the only thing which is clear is that if you like Database work, then Oracle is the right choice.
Check any online recruitment Web Site, for example,Monster.com, 
and search for 'database' and the number of Oracle-related openings is far greater than the second or third choices, 
(IBM DB2 and Microsoft SQL Server).