There are a ton of options out there right now, but some are less "sequiny" than others. I like the ones that are completely saturated in sequins the best.
These Express sequin leggings ($98) are reasonably priced and would look great with a loose fitting black tunic top and flats or a long boyfriend blazer, heels and a t-shirt.
The Mango sequin trouser ($99) has a looser fit. Love it paired with this tuxedo jacket. These are not quite as sparkly as some, but like how they flow.
The Topshop sequin harem trouser ($160) comes in electric blue, pink and gold.
These LaRok silver sequin ($348)leggings are pure rock n' roll with zippers at the ankle and pockets.