Vendor/Product Research
To make a decision, you have do tons of research. Talk to several vendors and get their literature. I think these were the two most important factors in reaching a decision:
Visiting vendor references and seeing the gear in action
Talking to AV techs to see what they like and dislike about the equipment they selected, plus how their vendor has done on meeting their service needs
When we went through the research process, I put together a small team and we visited two references from each of the three vendors on our shortlist. The team consisted of our marketing director (who participates in many of our presentations), and someone from administration who isn't shy about giving feedback. The three of us provided the selection information to our upper management to make the purchases.
Pricing is important, but it isn't the only issue. Getting good support and service after the sale is also very important. When all else is equal, however, spending fewer dollars always makes sense.