We do 70-120 every week. You are looking at a fair amount of investment to do that many birds. Do you have processing equipment already? If you already have that, it will certainly help on cost. We have a water heater scalder but we would love to have an automatic one. We use a tub plucker and the eviscerating is done on stainless steel tables. We have four adults working (one does killing, scalding, and plucking; the other three do eviscerating), and two kids (they go fetch the birds from the tractors and do any other odd jobs that come up). Today it took us a little over three hours to do 60 birds. We are improving all the time. When we first started, it took us 5 hours to do 25 or 30 birds. Just takes practice and getting the equipment so we can work in the most efficient manner possible.
Consider how you will brood them and how much the brooders will cost to construct. Same thing with tractors if you are going to tractor them. We run three large brooders and six tractors right now (the chicks get split into two tractors when they are put out on pasture). The waterers and feeders are a pretty hefty cost. We are switching to nipple waterers in our brooders, and we use bell waterers in our tractors.
We just bought an ice machine because we go through a lot of ice on processing day and it was just too expensive to keep buying bagged ice. Coolers or something like coolers to chill the birds in after processing is another thing to think about. We use five or six large coolers as chillers after processing, and we have another four coolers that we put the birds in after they are packaged. You'll need to consider packaging as well. We don't use shrink bags since we haven't found a label to put over the hole you have to make, that will stand up to being put back into a cooler filled with ice. We use 3mil bags that we close with metal clips and then our label is attached using a zip tie.