I’ve purchased several on Ebay and usually have paid in the $20 range or so for a rusty #4 with all of the parts included and no broken wood (tote or knob). I’ve also erred and purchased ones that were not standard #4s–I had one that I think came with a #3 sized cutting iron/chip breaker/cap iron. though I didn’t realize the difference until I had purchased a couple more. It annoyed me but it was also the first real hand plane I ever purchased and I used it to build my bench so it does have some nostalgia value to it. Ultimately I was able to pick up a correctly sized cutter/chip breaker/cap iron several months later so that plane, while somewhat of a Frankenstein (built with parts from multiple planes), is as good as any others.
As far as the one you’ve purchased, I think you can restore it just fine. My only observations would be that 1) the Japanning is pretty much gone (but you can put a nice coat of spray paint on it as part of your restoration) and 2) as others have pointed out, that cap iron looks pretty bad and you should probably try to find a replacement.