Quite a few items worth buying this Baro visit.

New Items

Rankings

Primed Continuity - +55% Ability Duration for Warframes. Serves a use on basically every Warframe.
Shell Shock - +60/60 Electric for Shotguns. Very useful for any build that uses or combines Electric, though the current elemental meta has made it relatively less common.

Primed Heated Charge - +165% Heat for Secondaries. A massive damage bonus to a really good damage type, sees use on a lot of weapons in a lot of builds.
Prisma Shade and Prisma Burst Laser - Sentinel and weapon. Above average survivability for a Sentinel, though this means very little now that Vulpaphylas are available. Notably offers a huge amount of MR, and the weapon is the only one (alongside its base version) that equips Pistol mods for the Augur mod set.
Tempo Royale - Stance for Heavy Blade Melee. My preferred Heavy Blade Stance, as it is quite mobile and fluid. Quite rare to acquire normally, so purchasing it from Baro or other players is worth consideration.
Quanta Vandal - MR10 Beam Rifle. Solid weapon, though offers little that other weapons do not match or exceed.

Prova Vandal - MR8 Machete. Badly outclassed, only worth purchasing for MR.
Sands of Inaros - Quest for Inaros. Always in Baro's inventory.
Baro Void-Signal - Key for exclusive mission line, awarding cosmetics. Can only be purchased and played using Inaros Prime. Always in Baro's inventory.

Corrupted Bombard Specter Blueprint - Offers nothing notable that other Specters do not also do better (most notably Warframe Specters).