I have a Medeli DD501 electric drum kit and need the USB to plug in my ipod. I think the type of cable i need is an a to b usb but with a ipod usb at the end. Anyone know where i can find one?

You can find the A to B USB for Ipods at a number of places! 
One is at Staples!  It is a Belkin Ipod USB Bpro cable that is selling for $24.99!
specifics are:
The Belkin Pro Series USB 2.0 5-Pin Mini-B Cable connects a computer or USB hub to a digital camera or other portable device with an A Plug/5-Pin Mini-B connection. Its advanced design is engineered to work with the latest digital devices, such as your MP3 player, PDA, and mobile phone. The Belkin USB Mini-B Device Cable delivers ultrafast, error-free data transfers and ensures top performance

Walmart has an Apple Composite AV cable selling for $48.88!
specifics are:

• Connects to your iPod or universal dock via the 30-pin dock connector
• Connects to your TV, home theater receiver, or stereo receiver via the composite video and red/white analog audio ports
• Also features a USB connector that you can plug into a power source, such as a computer, or the supplied USB power adapte

At the Apple store, they have a 10 ft. A to B USB cable selling for $19.95!
specifics are:
The Belkin Pro Series USB iMac compatible Device Cable lets you interface a USB device to a USB hub or a Mac computer host. You purchased the USB printer of your dreams, but faulty wiring keeps sending it error filled data. A Belkin Pro Series USB device cable will keep those dream machines error free