I have a couple set of blades...
The one that's installed right now, and another set that's sitting in my workshop awaiting sharpening.
They're in constant rotation.
You could do the same, but insstead, send your dull blades to a place like Sears.
Mine sharpens blades for something silly like $4.
A bench grinder (or some other form of high speed grinder) is a must for getting it sharp.
Of course, I live in the woods and cutting rocks and medium sized tree limbs are "par for the course".