I have bought a number of things from NitroPlanes and HobbyPartz as well. Everything came through OK.  The ARF planes were double boxed too.

Unfortunately quite a few ARF and RTF planes sold by many companies and stores do not have spare parts either. One has to double check, if they expect to need spares before the purchase as they don't always advertise it. There are some stores that stock spares for some planes, but you have to check to see if they have spares before you buy. Sometimes they never get the spare parts in too.

Now one time I ordered some retracts from HobbyPartz and they were backordered for a long time. I inquired about it and they refunded the money after a couple of weeks. So it wasn't a big deal to me.  But I haven't had anything damaged yet that I got from them, so I haven't tried to get anything resolved as far as that happening so far.