What equipment do I need to start djing with my ipod?

You could get started with a simple powered speaker like this one:

http://www.guitarcenter.com/Harbinger-APS15-15--Po...

It has the amp built in, so all you need is a standard 3.5mm to RCA cable to use that speaker.

If you want better sound, get a second powered speaker and maybe a pair of speaker stands.

If you're going to talk then you'll need a microphone, a cheap wired one is good enough. My advice if you want to do this for money, is to aim to have enough equipment so that if any part of the system breaks down, you can cope. For example, it's better to have 2 powered speakers, because if one breaks down you can still run on one. A powered speaker usually has several inputs, so you can connect the music player and a microphone. So my suggested minimum is

1. Pair of powered speakers

2. Pair of cheap dynamic mics. & leads

3 Audio & speaker leads as needed for set-up, plus spares.

4. Pair of speaker stands

5. Music player.

If you need to do it cheap I'd strongly advise buying better quality used gear over cheap new stuff, especially speakers.

If you go mixer/amp/speakers it may be cheaper, but buy a second amp for back-up, it's more likely to fail than mixer/speakers. If you use 2x powered speakers one can fail & the show will go on.

Always have at least one spare speaker lead, they are a common cause of failure. Get a spare music player too as soon as you can. It's not that disaster is bound to happen, but keeping back-up stuff will save you a lot of embarrassment, there's a fair chance that something will go wrong sooner or later.

There's a LOT of used gear on Ebay & if you have transport, you can get bigger, heavier stuff really cheap, not many people want to buy big, heavy used equipment, like 15" speaker cabinets. e.g. Peavey Eurosys are great speakers but are out of style & v. cheap considering their quality.