What are commonly needed repair parts?

I recently opened a Mac tech support business in Switzerland. I'm in the Apple Consultant Network here, but they won't let me be a certified repair location for 2-3 more years. Hence I source most of my parts from the US (like from iFixit!)

I'll be in the US in a month and looking to stock up on Apple parts and I'm curious if anyone here who repairs a lot of Macs has any comments on what are commonly needed repair items. Like, if you had $1000 - $2000 to spend on misc parts, what would you buy? I'm just talking about Apple parts - not hard disks and RAM.

I'm thinking:

• Top case/keyboard cables for iBook G4 and newer laptops (in case I break them opening the computer).
• Macbook Pro hard drive cables (sometimes hard to unstick from hard disks)
• Superdrive(s)
• Macbook Airport Extreme card(s)
• iBook G4 DC-IN board
• Screw kits?
• Keyboards for iBook G4 and newer?
• Fans?

What else?

Thanks for any input from Mac repair pros!

Thanks for the responses, guys! Sorry, I wasn't clear about something in my initial post, that is, I do mostly technical support and only occasional repairs. Maybe once a week I open a customer's computer and need an actual Apple part. RAM and hard disks I have good local access to, it's just the Apple parts that are not readily available here.

Unfortunately, as I live in Switzerland and am only in the USA for maybe one week per year, it doesn't really work for me to buy on Ebay or Craigslist as I'd need all of the purchases to be shipped to a hotel, and then load them in a suitcase to be taken apart when I get home to Switzerland.

Good point on maximizing every dollar, rdklinc, but for me it's more about availability of parts. If I have a customer who needs a new Macbook Airport card, I have to have one FedEx'd from the USA where shipping takes 5+ days and costs $70-$120 (and a lot of places won't even ship to Europe). My customers are happy to pay, say, 1.5x iFixit prices for the part, but they're not willing to pay 3x and also have to wait a week for the repair. So I'd like to build up a bit of inventory. And ideally without lugging a suitcase full of broken eBay laptops onto the plane ;-)

Thanks everyone!