I don't have time to do a good estimate now, but for each package you could get a good idea yourself by just counting the number of pl/sql procs and .tcl queries and multiplying by an estimate of how long you think it would take you to port each one on average. For example, if you had 20 pl/sql procs and you thought that it would take you 10 minutes on average to port one, and you had had 50 .tcl queries and you thought that it would take 5 minutes to port each one of those, then you would have a total expenditure of 20*10 + 50*5 minutes for the package.
You might also want to throw in some time for debugging and testing. Assume, for example that you will make a porting mistake on 10% of the queries and pl/sql procs that you port, and it will take you 10 minutes on average to track them down and fix them. Your total then might look something like (50 + 20)*.10*10 + 20*10 + 50*5.
As I'm sure that you're aware of, this is all highly subjective and dependent on your knowledge of oracle and postgresql. If you have a good knowledge of each system's flavor of sql then your average times for porting and testing will be much faster. Since you mentioned newbies earlier, the debug and test time and the number of mistakes made will probably be much higher than the times I mentioned here.
