Recently picked up a pack of Vindicators for my fledgling Space Marine Epic Armageddon force. Vindicators are not very popular in marine lists it seems so they were pretty cheap coming in at like 8 dollars in blister with shipping.
I only got 3 tanks so I cannot form them into a formation of 4 but can attach them to some other units like landraiders or devastators if I feel like or I might just model them up as part of the larger display force. In Epic these are MkIII vindicators but would be called MkI in 40K styling. The older styling fits in nicely with the Heresy era other components.
Similarly they have different side options. Mixing sides and hulls would give you lots of options for slight variance if you had many of these compared to the cookie cutter nature of the current models.