No, its really not. And there are very few Fire/Air combos. Fusion armors are nice, but they only save you probably 100K gold. The OP has 22Million.
The best way to get Guardian or Clayplate is a stone armor and Spectral captain (water/spirit). you're going to end up with some swamp shamans and some other crap, but you can fuse the swamp shamans to rocfeather for another try.
That is if you can't get ahold of some 4 star monos.
As to someone saying I've been extremely lucky fusing combustion, I've done it multiple times.. it seems to pop up pretty often. Roc/Infernal can throw it (less often than say, Cloud king/Ruby Plate), and can also throw Guardian, Pyromancer, or mono 4 stars. Mono 4 stars are really useful for fusing because you can fix one element.