AV is a specialism, so unless you have in-house AV expertise you should always consult an AV expert. You could hire an AV Consultant, but commercial AV Integrators are more often a better option for most organisations. An AV Integrator will do a site survey, make a needs assessment, assess your budget and provide recommendations on the appropriate hardware / software solution. They have relationships with AV manufacturers and can offer demonstrations and are able to get competitive pricing.