So, I've run into an interesting possibility. I'm helping to organize an event early next summer, a weekend long thing full of people who like (among other things) beer. The other organizers were talking about buying beer for it, but of course I had an alternate suggestion... Why don't I just brew it?

So, the thing I need to figure out is how to upgrade my equipment for less than it would cost to buy the beer. The plan is for three half kegs barrels, so I need to be able to do three 15.5 gallon batches. I'm currently brewing in a pair of 6.5 gallon glass carboys, and doing extract brewing in a 3 gallon kettle. I don't have a kegging setup, but my brother I brew with has a couple of corny's and a CO2 bottle.

So, basically, I'm looking for advice on upgrading my kettle, fermenters and kegging ability to be able to do three 15.5gal all grain batches at once kegged for an event. Any suggestions on keeping the cost as low as possible?