Conservatively, I would say yes, but I would need to know what kind of features do you need on this mixer. Is it important to have more than two auxes, do they need to be pre/post switchable? Do you need stereo channels? Do you need expansion options, such as FireWire out? Do you need EQ, and if so, do you need two mids? ALl of these things affect the price of the mixer greatly.
In the mean time, you may want to look at the following boards:
I personally think it will be a challenge to find a board with a built-in amplifier for under $300 (at least, a quality one that will last more than a few years). However, you might consider looking at an inexpensive board (see above), and then an inexpensive amp to go along with it.