Every writer should be checking posts on Writer Beware on a regular basis to keep up with all the new scams out there. Here's this week's: Impersonation
A simple rule to follow: don't ever pay anyone anything. Money flows to the writer not to the publisher/agent.
The only exception is that some literary journals charge a $3 submission fee to pay for their submission software. This seems reasonable to me because it would cost about $3 to mail in your manuscript, if anyone still used the mail rather than one of the three or four industry standard submission systems.
Sometimes legitimate contests charge $$ to enter. I have occasionally entered a contest that charged in the $30 range, but only because the submission fee included a subscription to the magazine, which was also around $30, and I actually wanted to subscribe to that magazine. I generally don't go above $5 for contest reading fees otherwise, because the odds of winning are just too low to justify the expense. If you want to give away your money, buy a lottery ticket instead. I never-ever pay $$ for contests that are not associated with a magazine I'm already reading or a charity I support (e.g., I'm happy to pay $5 to enter the Merril Collection SF&F fiction contest). There are a number of contests that charge hefty fees as well as demanding hard copies of your book, but these often appear to be pure scammer. Again, see the post from Writers Beware on contests for details.
Generally, if you're paying someone else, you're being had.