I found some heavy nice bond paper tucked away at home that I forgot I had. I bought it years ago for printing resumes on (I guess printed resumes are passe now...) I'm not sure what weight it is, but it's pretty stiff. You can hold one bottom corner of the page and the paper will stand upright in your hand without you having to finagle and try to balance it. So quite heavy. I bought it at some office supply store.
I tried this heavy paper for targets and the wadcutter holes were perfectly clean! I seem to remember it being moderately expensive back when I bought it - maybe 5 cents a sheet (8-1/2x11 standard letter sized paper). Still, that's cheaper than buying preprinted targets. It goes through my laser printer just fine. I remember using it years ago in my inkjet printer too, with no problems.