We have found various retail items for tanning and lashes very good but it depends what you are offering as treatments and it works best if you can tie it together, ie if you are offering spray tans it is very effective to offer tanning retail items, as it doesnt only help in skin preparation and aftercare but also keeps the tan lovely until the client comes back to you.
The same goes for other treatments so you could link it together for lashes, nails etc?