I'm trying to come up with a poisones swarm team. What cheap characters are their that have poison and good mobility such as LC or PT?

WoS sandman has phasing on his first click, then you push him into stealth, plasticity, poison, and a SP that deals 1 unavoidable damage if they fail breakaway.

edit: Oh you want CHEAP guys. my bad. Sandman is like 101 points

is impossible man cheap enough?

These are the clix you're looking for:

SF102 Blanka 50
CA039 Eel 64
SI052 Impossible Man 72
AA015 Plasmus 80
UN037 Chameleon 30
WS060 Vapor 79
MM046 Cloak 47
CV002 Ghost Widow 54 (best of the bunch)
AA035 Ghost Fox Killer 68
CR006 Shimmer 49

On a side note remember that at the beginning of your turn you can use outwit before poison.

As side from the cheap clix with poison some higher point clix are nasty also, and your going to need someone to lead your cloud of poison.

WoS Sandman 101pt
IH Red Hulk 178pt Full dial poison
CA Red Skull 140pt Full dial poison