You can always try to look further out, I don't think you can find sourcing mission where you have to jump just around the corner. I did some sourcing missions in the past and I had to travel pretty far, that's the idea. After all you flying an Anaconda, so even 500 Ly is only 10 minutes (or less) away for you. Also keep it in mind that in order to have better missions you have to build your reputation with the local factions at whatever station you choose. If you just keep jumping around different stations and systems you going to have lower tier missions because for the locals you're a stranger. Also, if you looking to buy a Cutter and trying to build your ranks with the Empire those sourcing missions are useless. You need bunch of stackable data delivery missions with high reputation gain and small or medium ship instead. If you want sourcing missions for your Anny just because you like them, that's completely different story.