How about a used f2.8 tele zoom? Once you get up toward $1,000, you can get a used 80-200 f2.8D for $700-1,000, maybe less. That is a great portrait lens if you want to get a little further away from your subjects.
I don't shoot weddings, but I find that it's hard to shoot live subjects at f1.8, because the DOF is so shallow.
That said, the 85 f1.8D is a great lens at a great price new or used (especially since the newer AFS 1.8 and 1.4 lenses came out). It's certainly capable of great subject isolaton.