I'm in a similar position with the DMG.
There are only a few things I use the DMG for.
1) Treasure generation
2) XP calculation
3) Magic item listings and generation
4) That damned "Starting Wealth" because we never make lvl 1 characters
5) Occasionally calculating cities, city wealth, and NPC classes in an average city
6) I do NOT use the sample characters because they suck, and it's stupid to use them. One of my friends recently started DMing a campaign and he lives and dies by them, even though he acknowledges that they suck. He's just too lazy to draw up his own NPCs. This came to a STUPID point last session where we were fighting PIRATES... and they were all fighters. So, by the tables, that meant that all these pirates were swinging on ropes over to our ship wearing full plate mail armor and bastard swords. Can you say STUPID??
So, for options 1-5, I'm at a loss for why I need to pay $30 for just a few little tables.
The unforuntate thing is that I use those tables so often, I think it'd be a pain in the ass not to have them be compatible with my PHB and MM... especially the magic item table, which I think is really the only thing on that list that's changing.