Picked this up the other day, Craigslist find for $80. The cheapest I have seen in a while. Does anyone make a replacement spring for these? I know most people make their own but I don't think I know enough yet to put the tool at risk of a bad part. Disassembly and clean up begins soon. Anything I should watch out for? 

Considering that you can make a spring for it by just bending a piece of mild steel cold; perhaps you do know enough...  Do remember to take apart the pivot area and clean and oil it as that will help a lot with the spring working well.

I don't need any particular type of spring steel or anything?

Nah, spring steel isn't necessary for this application. All you need is something that will tension a little bit when its closed so that it opens with ease. 

is it also missing one of the keys/wedges, sorry I couldn't quite tell from the picture. there should be two.

                                                                                         Littleblacksmith

Not a problem and now you can make it to fit with your new spring installed!

Is the wedge what keeps it tight against the mount?

yes.

                                                                                     Littleblacksmith

You're lucky; most cheap vises are missing the mounting hardware. Nice find!

heres a couple of pic,s of the wedge and spring looks like

Awesome, thank you.