Yamaha DTXpress/DTXplorer/DTXtreme

Hello,

I was considering putting a kit together for my 5 year old.  I was 
debating between a dtxpress II/III or a dtxplorer.  The dtxplorer is 
attractive for this purpose because it seems smaller, but I think I can 
get more for the money with a dtxpress II off of eBay.  Has anybody 
done this?  Any suggestions are welcome (including other brands or 
kits).

Thanks,

Jaime