I don't think you'll get 85 herblore, maybe 82-83, max 84. And there's not much you can sell either. 4m is locked up in very important items (Slayer helm, whip and misc). So you have 38m to spend. If you want to be sure you'll make it, make an extra 8m or so. (66 > 88 will cost me 50m, and I'll be able to start at higher potions, taking better advantage of my 2.7 and 2.55 bonus)