Combine two amber amulets of vermin and reskin
The bracelets of loyal vermin that the question describes can be made by combining into one magic item an amber amulet of vermin (giant wasp) (Magic Item Compendium 68) (800 gp; 0 lbs.) and an amber amulet of vermin (giant stag beetle) (ibid.) (1,200 gp; 0 lbs.). Such an amulet has a price of 2,400 gp. (This figure is reached by adding to the higher-priced item the price of the lower-priced item +50% as the Compendium details on Improving Magic Items (233).) Making this amulet of vermin (giant wasp and giant stag beetle) occupy the arms slot shouldn't change its price; it remains a slotted magic item.
Unless I'm missing something, these two items combined have exactly the effect described by the question's original magic item, the bracelet of loyal vermin.
Exercise caution with the amber amulets of vermin
The amber amulets of vermin are, at low to middle levels among the game's most competitively priced magic items, easily obviating many encounters and staying relevant at least as a means of short-term flight sometimes to a campaign's early mid-levels.
This DM doesn't ban the amulets, but my campaigns' gentlemen's agreements see me wait to use them until the PCs do, and if the PCs never do then the I don't either, and if the players consider getting some amulets, I make it clear that I am comfortable with the campaign becoming a very, very bloody version of Pokémon. That's not to deter them or to threaten them but to explain my own need to maintain the campaign's verisimilitude: societies must be built around amber amulets of vermin because every level 2 commoner can afford to have 1/day for 1 min. a flawlessly loyal CR 3 Large or CR 7 Huge monstrous scorpion, and, y'know, that's kind of big deal. (As is, by the way, the difference between CR 3 and CR 7. So you know, that depends on if the DM views the errata issued for the Compedium (Mar. 2007) as impacting the reprinted Compendium (July 2013). Sigh. Also see this question. This DM really hopes the reader doesn't have to care.)
Like boon traps (see this question) and glyph seals (see this question), amber amulets of vermin are something a DM must plan his campaigns around if they are commonly available at the listed price. Culture changes if everyone who is even slightly competent has a horrifyingly powerful siege engine dangling from his neck.