Mexican hoggies are a different species.
They are probably most closely related to western hoggies compared to the other snakes in the genus Heterodon.
Price is probably in the $150 region perhaps? I wouldn't expect to spend less than $100 each, they aren't very common in captivity.
Color is a bit different than westerns, and have a stronger 'desert-y' camoflage to them. The pattern of spots across the back is different too. There are some minor structural differences in scale count (I think) and the nose comes to a stronger point.