how much is it and what equipment (other than a laptop) would I need?
Fruity Loops Studio costs $99 at its smallest package
http://www.image-line.com/flstudio/ "Fruity Edition"
You don't really need any other equipment to use a DAW (Digital Audio Workstation (Examples: Ableton Live, FL Studio, Reason, Etc.)) as long as they come with virtual instruments/synthesizers that you can play with (I'm pretty sure all DAWs come with at least some stuff no matter what sized package you buy, I know FL Studio does at least). Of course, you can also just record your physical instruments into the program and play with the sound there.
Although, a lot of people like to purchase MIDI controllers to control different parameters, or playing the virtual instruments, in their DAW of choice. You can always just use the built in sequencer in whatever DAW you're using to make melodies or whatever.
Personally, I use a physical brown townog synthesizer along with a seperate effects processor and run it through an audio interface and record into Ableton Live, then I play with the audio files until I like what I hear, so I don't really have much experience with digital synths. For drums I download and alter any free drum sounds I can find on the internet and then build a drum beat with Ableton's midi sequencer.
As far as I know most DAWs have pretty similar core mechanics.
