Just say you can't go. There is no reason to stress about the gift. If it is someone you haven't seen or talked to in a long time. However if you want to be nice you could do it. I sent a babygift to a first cousin of mine when she had her first. I haven't seen them in a long time, but wanted to congratulate her. I was very disappointed when I never heard anything else about the baby. Only through other family members. I was at least hoping for a picture.