A couple years back Reaper Miniatures, through a successful kickstarter campaign, re-introduced their Combat Assault Vehicle (CAV) line in their hallmark Bones plastic. By casting their CAV line in plastic, Reaper has reduced the price of these models. The CAV models are priced between $6 to $7 (US dollars) each, which means you will get high qualities mechs with a minimal amount of strain on your wallet.
72212 Emperor (left) and 72224 Imperator (right)
72227 Tyrant (left) and 72225 Dictator B (right)
Modelling Tip: Some of the CAV models had their guns bent in odd directions. This issue can easily be resolved. Before I start gluing the miniature to its base, I microwave a large mug or small bowl of water (for 2 1/2 minutes). I place my bones models in the hot water a couple of minutes. This allows the Bones plastic to become soft; in most cases the model will revert to it's original form (sometimes you may need to hold the model part in place for a few minutes).
72224 Imperator (left) and 72225 Dictator B (right)