If you are ordering only for yourself (getting parts outside of a coop), I would recommend reviewing each part in the BOM to see where you might either save yourself some money or get spare parts at little, if any, additional cost.
For example, for the SSCs, the resistors (291-150-RC) are $0.0540 for 10-199, and drop to $0.0190 for 200-999. For the 60 SSCs in the example you gave, it would cost you $3.24. But for $3.80 you could get 200 total resistors, and have plenty of spares for other projects. It will cost you more, but still would be less than shipping costs if you needed more in the future.
Even better, for the 291-4.7K-Rc, you need 120 of them. At $0.054/ea, that is $6.48 for what you need. But if you increase to 200 of them, the price drops to $0.019/ea for a total of $3.80. Which means you spend $2.68 less and get 80 additional resistors. It's a win-win, and a no-brainer in my book.
As RJ indicated, you aren't likely to get price drop talking to anyone as Mouser for the small quantities of parts you would be looking at. But carefully looking at their standard price drops for the parts you need might save you some money.