And don't forget the biggest expense, the wood for the continually burning fire on the altar of sacrifice. If you just add up the daily sacrifices not on a Holy Day you will see that that was a whole lot a cookin' going on! Some sacrifices had to be completely burnt up, reduced to ashes.
If you want to read up on the courses that Henaynei spoke of go to 1 Chronicles 28. There you will see how HaShem himself gave the plans to King David for the temple and ordered the Levites to serve by certain divisions. They were divided up into 24 courses so that they each took turns serving the L-RD in the holy Temple. There were also several "classes" of priests, such as Singers, Musicians, Gatekeepers, treasure keepers and Assistants to the other Priests. Each course served twice a year plus 3 weeks.
The priests and the Levites were divided into 24 courses within their assigned class. The length of each course was 7 days . The week of service began and ended on the Sabbath . In addition, all the priests served for 3 extra weeks during the year .
Each course of priests and Levites came on duty for a week, from one Sabbath to another. It should be made clear that not every priest and Levite in a course served every day. The service was subdivided among the various families, which constituted a course. The number of families in a course varied. The singers had only one family in each course whereas the other classes had up to 9 families in a course.
It also must be remembered that another "duty" of the Levitical tribe was the "keeper of the law". They were to be the teachers to the people of HaShems law handed down to Moshe. In the "New Testament" they are referred to as the "Priest and lawyers" for they were the ones who interpreted the law.
You will find today many a Cohanim that are attorney- of secular law.
Here is a link that might help you.
http://www3.telus.net/public/kstam/en/temple/details/priest_service.htm