Vouchers are a great gift idea for everyone!
It allows your friend to choose what they want, and when they want to use it. I always allow a 3 month expiry date to make sure they use the Voucher promptly within this time frame.
With a gift of a $100 voucher, I usually offer a 1 hour Tarot reading which includes some Numerology and Astrology to look at the big picture coupled with more indepth information using the Tarot cards.
They also have choice to mix and match products and services that I offer.
For example, a 30minute reading is $70 then they may choose some product for the remaining $30.
Or have a Reiki Healing for $60 then use the remaining $40 for some products.