speakers for old yamah mixer

a friend has an old Yamaha EM150 ss mixer with 75 watts.

She is looking for speakers to go with it that are not too expensive (less than a few hundred dollars), just something that could handle some power.

Where would I look for these?

Ebay has lots of stuff but is there another source to find out what model to buy etc...

ANY suggestions or information is welcome

thanks

Phil