[Claudius]

Frank, I know exactly where you're at right now. All the thoughts you listed (what to get next, spare planes for disaster, etc) feel very recently familiar...

I remember asking around the field about this same question maybe 10 months ago, wanting the magic answer and (sorry guys!) not getting any. But... well... you won't get one from me either

It just seems to happen.

If you're flying, then it's spare props (like Gary, if I'm ordering one then I'm ordering a few), batts, glues and bits for minor repairs to keep the planes in the air. Have found a wattmeter, prop balancer and cell voltage checker to be worthwhile investments.

If you're also building/assembling, then definitely servos, an ESC or two in the size appropriate for the planes you're hunting, a spare receiver or three, ESC<->motor connectors, battery<->ESC connectors, wire, heat-shrink tube, hinges, ...

Like a couple other responses here, I've also taken to keeping a list between orders, and doing the "postage filler" thing with smaller items.

And I've also come to just accept the frequency with which I realise I "need" something else right after my last order gets shipped That said, having a couple projects on the go at once lessens the pain (since usually only one of them is stuck at any one time) and this also seems to be getting less frequent as I build up a stock of bits.

Hope this helps!