To produce and share narrated video slideshows, you will need the following equipment:

Digital camera(s) or camera phone(s)

Computer(s) with Internet access and a microphone input

Microphone(s) 

Notes

The microphone need not be expensive. In fact, expensive microphones generally cannot be connected to a computer without additional equipment. Headset microphones are generally fine.

To record dialogue, you may consider a digital voice recorder or a digital audio recorder. The first type is less expensive but you should make sure the "static" noise from the mike is acceptable to you. Sometimes the problem can be solved by setting the sensitivity to "low". Digital audio recorders are designed for music and, coupled with a professional mike, can give outstanding results. However, their cost  makes them unsuitable for most EFL/ESL projects. 

If you have a recent laptop computer, it may have a built-in microphone.  This will generally be fine for both monologue and dialogue.