Do you have like a masterlist of all the episodes gaara is in / perhaps know of a site that has one?
Actually I pulled this list for a friend of my wife's a while ago, so here you go:
Episode 21 (First appearance) - I actually think our first glimpse of him is in Ep 20, but 21 is probably his first "scene"
Episode 34 (Forest of Death)
Episode 48-50 (Gaara vs Rock Lee)
Episode 58 (Hospital)
Episode 65-67 (Gaara vs Sasuke)
Episode 74-75 (Gaara vs Sasuke cont.)
Episode 76 (Gaara's past revealed)
Episode 77-79 (Gaara vs Naruto)
Episode 125-127 (Gaara and Rock Lee vs Kimimaru)
Episode 216-220 (Ultimate Weapons Arc)
And entering Shippuden...
Episode 4-32 (Kazekage Retrieval Arc)
Episode 182 ("Gaara's Bonds")
A critter who steals Gaara's form appears in Episode 186
Episode 198 - onward (5 Kage Summit Arc)
Naruto the Movie 2 Stone of Gelel and Naruto Shippuden the Movie 3 Inheritors of the Will of Fire
And then there's this list from Reddit regarding his filler episodes:
Gaara has a filler arc at the end of the original Naruto, episodes 216-220.
In Shippuden, he has two individual episodes for him: 182 and 388 (388 is mostly just a recap of Gaara's story so far, though).
He has a few minor scenes which were not in the manga in the episodes just after the Five Kage summit arc. Basically war preparation, nothing really major or character developing.
He is also a main character in the Second Chunin Exams filler arc, from 394-413.
There are more episodes that he's in in the war, but I don't know the episode numbers. There's the light novel Gaara Hiden: A Sandstorm Mirage, which is pretty great. And of course he's in my favorite episode of all time, #497 where he and Lee go on their date :)
