Hi Gravelman,
As Darryl mentioned, we need a little more info to pin this one down, the values of the manual will depend on many things, such as condition, but one of the most important factors is age.
The first corvette was run from 1963-64, and was released through the early and mid 60's with a new model each year, at this point Victa was giving each one a manual of its own.
Towards the end of the 60's the corvette was broken into two lines, the 125cc and the 160cc, and for the last few years of the 60's it was released with 2 new models each year.
Throughout the 70's it took a back step to the VC-160, then the VC-Mustang, and numbers sold were low, towards the later part of the 70's production was low for this model, and at some points in the 70's no new models were released, they just continued the sale of previous year models.
Throughout the 80's the corvette saw only one major change, the shift to Powertorque, and as such, there was only a handful of actual different models, at this point also, manuals started to be printed in broader spectrum, each one covering many models.
Throughout the 90's and 10's the corvette was often run in multiple simultaneous lines, with different engine options and setups, sometimes up to 6 corvettes were available at any one time, however manuals by this point were generic, and few mowers did not come with the one "Victa Mower" manual.
So seeing a few pictures of your actuall manual is important, to help work out specifically when it relates to.
Try and focus, if you can on any pictures or sketches of the actuall corvette covered, if we can ID the models shown in it, we can ID the era.