Gift voucher (as a gift) for wedding you aren't attending

DH's niece is getting married next month, 13 December.

We won't be going to the wedding. Travel costs, children not allowed, too close to Christmas (oh and now he's booked me a holiday in Port Douglas ;) )

Anyway, I've sent off our inability inside a lovely engagement card.

I thought it would be nice to send them a wedding card with a gift voucher in it.

$50, $100 ....more??

They are in Perth so next question is:
Myer, Ikea, David Jones, other?

They specifically requested money, which I won't send in the post - but I suppose I could get a money-wotsit from the post office....

I'd send a cheque. Then they can put it towards whatever they want. Or do a bank/paypal transfer and send a card.

I would probably do a gift certificate for $100 for friends and $150 for family. Maybe break it down in a couple of vouchers for different stores.

Another option is to contact a shopping centre near them and see if they do a voucher for the centre. Many of the shops in the centre will take the voucher (often except the larger stores like Coles, Kmart, Target or Big W though) so they are not limited to just one store.

I would send cheque or do bank transfer, they might have something specific in mind like a holiday or from a specialist store that doesn't do vouchers.

I always think the greatest gift is to give someone something they want/have asked for. For our wedding work gave me money (had not requested anything but they knew me well enough not to buy anything) and we got some of my artwork onto canvas for the wall (we will love those forever). I also think it is a way of showing your respect for them in that you are happy that they will put money to best possible use for them.