Pricing for the resident meal plans is set by Eastern, not Sodexo. You can find pricing for the resident meal plans at Eastern's website, or by looking at the meal plan charge in the tuition bill.

The four resident meal plans all have the same price. This lets students choose the meal plan they want, or change meal plans after the semester starts, without adjusting their tuition bill or financial aid.

Eagle Dollars and Flex Dollars are mostly the same. The are both funds stored on your student ID like a debit card. 

Flex Dollars: 

Are included with resident meal plans.
Are only used at the four dining halls on campus
Are linked to your resident meal plan. (If your residency status changes, you might lose your unused Flex dollars.)
Expire & refill between semesters. 

Eagle Dollars: 

Are either purchased as add-ons to a residential meal plan, or as part of a commuter meal plan.
Can be used in the four dining halls on campus, or in the library printers. Do not expire, even if you study abroad, graduate, withdraw, etc. (Note: After three semesters of inactivity, unused Eagle Dollars are cleaned from the system. We keep paper records, and will restore them for up to seven years later).
Both Eagle Dollars and Flex Dollars are nonrefundable and nontransferable.