Another option, which I saw on another forum; get one of those 10" water filter housings (or better still, get a double or triple unit). Fill with colour-changing silica gel beads (orange when dry, green when saturated). Fit just before your gun airline. This should dry your output air sufficiently for the sandblaster.
When the gel becomes sufficiently wet that you start experiencing clogs again, remove the gel, bake in a low oven until orange again; then replace and continue. I assume there will come a time when the silica beads break down and become useless, but you should get many cycles out of it before you need to replace it completely.