A lot of the pain comes from cleaning every single cartridge. Many old games look like this:
http://i.imgur.com/sdRqyl.jpg
And you need them to look like this:
http://i.imgur.com/GbxMxl.jpg
That takes about a half hour's work. Then you get to open the cart and clean the contacts, another five minutes. Then once it's connected to an SNES and powered on, you have to wait 5-10 minutes to dump it, and then move on to the next cart.
It's a full-time job for several months to do a complete PAL set. And that's not even counting scanning the boxes, manuals, cartridges and PCBs :/
It's a lot less effort for the donor to send me his games, and I send them back, and reimburse him on his shipping charges.