With Games Workshop currently not having a model for Mycetic Spores, a while back I bought a few "Mega Bloks - Plasma Hatchers" cheaply on Amazon. The idea was to do as little work as possible but still look good and fit in with the rest of the army. These toys fitted my requirements perfectly.
Knowing that somewhere down the line that GW may well release a Mycetic Spore model I didn't want to spend a fortune or too much of my time on completing them. I bought 3 of them and paid about £3.00 each, so it's no big deal if I ever need to replace them with an official model.