Cat5 and baluns wouldn't even be breathing hard, if you wanted to do my 4 for $400 deal it would actually be $380 and you would get two of the 4in1 baluns to use as a link, then wire the building with RG59u. Or you can go the standard package and run Cat5 to the cams.
That answered your question however I would STRONGLY urge you to use a wireless data link and IP cameras or streamers. This will cost you more today but be more future proofed and allow additional funtionality.
600' is too far for wired ethernet without a midspan, using a data link would allow for ethernet in the shop too which can be nice and cost ya nada.
I am making the assumption you have power to this building already...
