It seems hard to figure this out.
Searching google for the last 30 minutes it seems that there isn't one definitive answer.
An article I found from ROSS TUCKER regarding UDFA says :
http://sportsillustrated.cnn.com/2008/writ...ents/index.html
"Every undrafted free agent signs a contract for minimum salaries, so the only negotiation revolves around a signing bonus that ranges from zero to $25,000. I have always felt it is critical to sign with a team that will offer the best opportunity to make the team, not necessarily the team that will offer a couple thousand dollars more up front. The serious money comes from making a 53-man roster or even a practice squad. However, turning down more money can be easier said than done.
Though the difference between $5,000 and $10,000 may not seem like a lot given the current salary cap climate and huge dollars given to top draft choices, $5,000 is lot of money when you don't have any. For your typical college kid with $58.37 in a bank account and some credit card bills to pay, it is often difficult to see the big picture. Still, players and agents must weigh the bonus money vs. the potential opportunity that they deem available."
So, what is the minimum salary ? And, if you do not make the team do you just get paid a few weeks worth of that minimum ?
According to ASK THE COMMISH here are some #'s (mind you these are the #'s for 2007).
http://askthecommish.com/salarycap/faq.asp
Minimum salaries have changed as follows:
Years 2007
0 $285,000
1 $360,000
2 $435,000
3 $510,000
4-6 $595,000
7-9 $720,000
10+ $820,000