Find a haberdashery (wot is a shop wot does bits fer yer clothes) or hobby / crafts store.
I suspect the people who sell small packets of beads and sequins to tackle shops buy them in these shops, then get worker elves to put them in small packs for us to pay the same price. E.G. 500 x 3mm clear beads, about £2. More sequins than Shirley Bassey's dress, about £1.
They don't do swivels, which is a shame, but the shop lady said dresses don't need them.
So's they don't guess what I'm up to and ramp their prices up, I generally pick up a yard of chiffon for cover...... MK