With a 30 qt pot, I am assuming you are doing a full boil for a 5 gallon batch. I would recommend a chiller in that case. With a partial boil (3 gallons), ice works pretty well - I could use the ice from my ice maker plus a bit from a bag and the cold water from the tap and be good to go. With a full boil, however, it was a bitch to get it cooled down fast enough. So, I ended up buying a chiller from learntobrew.com - $73 shipped for a 50 foot copper immersion chiller with garden hose hookups. They also have a 25 footer for quite a bit less (I think it was around $48 shipped). I could not build it for this price with the local copper prices! They also have $8 flat rate shipping, so you can grab some other supplies if you need to save on overall shipping.