Yamaha DTXpress/DTXplorer/DTXtreme

Hi,
 
I just bought my first set of electronic drums (Yamaha DTXPRESS).
 
I have never played drums before, so I am trying to stay inexpensive 
as I don't know if I will pick up the hobby or not.
 
I have the basic Yamaha kit, but it looks like I need a few more 
items. Can you please recommend a (inexpensive) amp, a pair of 
headphones, and a drum pedal that will work well with my kit.  Where 
to find the items would be helpful also.

Any help would be appreciated.

Thanks!

Jason