There are other considerations besides price and your time. Availability, for example. If I needed that printer for a project that had a deadline, there would have been a cost associated with getting it too late to do that project. That situation may have made it worthwhile to pay more in order to get it sooner. How about out-of-pocket costs to purchase item? If I had to drive 100 miles round-trip to save $30 on printer, is that a good thing to do? No, because it will cost $34 in auto expenses (at current IRS rate of $ .34 per mile). Not to mention time it would take. Unless I really need that printer right now, it doesn't make sense, does it?

The point I'm trying to make is that, no matter what you purchase there are tradeoffs. Time versus money. Convenience versus money. Opportunity versus money. Be sure that you consider all of factors, not just 'sticker price'. Whether you like it or not, true cost is a combination of all of those factors. Saving money is great. But it's gonna cost you!

In a case like this, you should always try to test out equipment BEFORE you give presentation. As you test equipment, make sure that audience can see and hear visual aid. Most importantly, become familiar with how to use equipment. The last thing you want to do is hit "record" when you mean to hit "play"!

This same principle holds true for all visual aids, whether they are audio clips, computer presentations, or even posterboards with graphs written on them. Always try to test visual aid in actual setting, and try to imagine potential problems that could occur.

As a last piece of advice, always have a "contingency plan" ready in case your visual aids fail you. It might not happen, but if it does, at least you will be prepared for it!