I know this problem. I'm in a similar situation. Got two vouchers at €50 each for a big shop. The first thought was to simply get two sets of new elixir strings - always helpful. But i'll buy strings when i need them no matter what, and these are gift vouchers so i need to get something i normally would not buy. One hundred is not enough for a U-Bass and any pedal i'd look at is a lot more expensive as well.
So, something nice, luxury and useful:
-A set of Lava or George L Cables if the player is using a pedalboard.
-A supernice Strap, wide, leathery, cushioned (with security locks if normal pins are used)
-A Luxury Softcase Gigbag
Carvin Club #295