At our salon, we offer brow tints and shapes, and lash tints. They are popular treatments, and what some clients regard as a necessity rather than a luxury.
I have found a lot of clients will come in for 'smaller' treatments (bikini/underarm wax, standard false lashes, as well as ebs, ebt, lash tint) as their first visit to the salon, and then return for 'bigger' mulitple treatments. So offering the 'necessities', is a good way to gain a regular client coming back for the 'luxuries'.