The satyr's gear may not change its challenge rating
A satyr druid 5 has either 4,300 gp because it's a level 5 NPC druid and, in addition, around 4,500 gp that's average treasure for an EL 9 encounter (DMG 51) or 7,200 gp because of its ECL 7 (MM 291). (More can be read about this contradiction in this question.) The DM should pick at the campaign's beginning how to determine the wealth of a monstrous NPC with class levels. This DM strongly recommends the first option; the second option is absurd. (For example, under the first system a CR 8 hill giant fighter 1 has 900 gp plus around 3,400 gp that's average treasure for an EL 8 encounter, while under the second system the same hill giant fighter 1 has a whopping 100,000 gp because it's an ECL 17 NPC.)
(This DM recommends a middle-ground house rule saying that monsters with class levels use their challenge ratings as their NPC levels for Table 4–23: NPC Gear Value (DMG 127) and have no other wealth or treasure, eliminating the quirks that come from random treasure determination and avoiding the mid- and high-level excesses that come from using ECL. I've used this, and this works fine, but it is a house rule.)
Once the DM's determined how to figure the foe's wealth, subtract the value of the creature's gear from that wealth as one would for a PC. If there's leftover cash, spend it or make it part of the creature's hoard. If a little too much has been spent, that's okay. The creature will be somewhat stronger, and players should expect that sometimes. Some creatures will be lucky enough to have more stuff, just like PCs at times might have too much stuff. The PCs caught the monster on the upswing, and that happens. If the monster's defeated, the creature's excess gear should be compensation enough for a slightly harder fight.
If the creature has an excessive amount of useful gear—like, for instance, a satyr druid 5 with a half-dozen doses of the poison black lotus extract (DMG 297) (4,500 gp; 0 lbs.), each of which can drop a PC on a lucky roll—, recompute the creature's wealth as if it were a PC using Table 5–1: Character Wealth by Level (DMG 135). If the creature's gear remains at or even slightly above that new threshold, consider increasing the monster's challenge rating by 1. (While this is unofficial, such a tack is taken by, for example, at least one NPC from former Dungeon magazine publisher Paizo's original 2008 Rise of the Runelords adventure path, and that seems reasonable.)
If the creature's gear is vastly in excess of its wealth even were it a PC, it's probably a good idea to reduce its gear rather than increase the creature's challenge rating. Remember that PCs are supposed to win fights, and while giving a monster excessive gear makes it tougher, a monster's gear is also a reward for defeating it. Now imagine the PCs developing a clever plan that kills the monster without them taking any risks, scoring all that juicy loot without expending resources. If that much free loot would unbalance the campaign, reduce the amount of loot instead of increasing the creature's challenge rating.