Welcome aboard, UnderMeSensi. Like I said in the first post, anything related to organic gardening, composting, veggies, etc is all fair game in this thread as long as we keep it positive.
I think the cheapest and easiest DIY worm bin is a simple 10-gal Rubbermaid bin with holes punched in the bottom and sides. You want the shallow ones; I think they are about 7-8 inches tall, or something like that. This should set you back less than $10, and it'll last forever. I have three of these going, and have had nothing but great results. Here's a link to a great page about worm composting:
www.redwormcomposting.com
This page is where learned much of what I know about worm composting. The author is a great guy, too. He was quick to answer a couple questions I asked him via email.
I'm curious... How were you planning to integrate the worm bin with your existing compost pile? How big is this pile, and what's it made of? I ask because you may have better (faster) luck by simply correcting the C:N ratio, moisture level, and aeration of your pile so it'll heat up to 140+ degrees F at the core. This will REALLY speed things up for you.
Either way, I HIGHLY recommend starting a worm bin for your kitchen scraps, coffee grounds, etc.
Good luck!