I've been invited to my brother's wedding in a few weeks. The invitation has a poem requesting cash towards the honeymoon instead of a present. My own wedding is 2 month after his, so money is fairly tight at the moment. Really tight, actually.
How much will be ok as the gift? My DP, our 2 DC (preschooler and toddler) and I makes 4 of us invited. My brother and his wife to be are much better off than us (and they know this) so I don't want to give too little as I'd feel embarrassed but obviously I don't want to give too much 
I just don't know the etiquette regarding cash gifts, I haven't even mentioned gifts on my own wedding invitations because I'm clueless!