is what I would say

is what James would say ;-)

Ich denke, das sich das doch sehr gut anhört

"you may now help yourself (yourselves) from the Buffet"
or
"the buffet is now open"
are good options.

The suggestion by KanzlerPalpatine doesn't quite sound right, -that would mean that you can start with the refreshment bar, & then when you've eaten everything on there, you can go onto the dessert bar, and then you can go onto the alcoholic drinks bar, ...etc.
replacing "bar" with "buffet" would be a step in the right direction, but still doesn't quite sound right, somehow.

Dictionary: bazar
"bazar" ist doch ein Basar (sowas wie ein Markt)
Ich würde eher "buffet" sagen...