There are many places to eat around town that will be cheaper than the Brasserie, which has OK food if somewhat stilted (short menu, relatively high prices.) For typical Mainzer food try the oldest restaurant of Mainz, the gasthaus "Specht", a traditional inn since 1594, cozy, friendly, near the Gutenberg museum and Schwann hotel, iirc. Lots of places to eat - even a fish restaurant down the river street toward the antique ship museum.