When we got married, I bought the wedding party their dresses and my husband paid for all of the tuxedos. Our friends had plenty of money, but we were asking THEM for a favor. We also chose just 3 bridesmaids and 3 groomsmen.
My husband was thrown a bachelor party within driving distance for a 3 days weekend on a houseboat. I didn't want a bachelorette party. My MIL threw me a bridal shower where we were currently living and then my mom threw one where I had grown up and where we would eventually return. I hated those parties....but both of them insisted. They both told me that it was more for them. One was housewares and the other was lingerie. BOTH should have been lingerie. ;)
Our wedding ran $30k. I wanted to go to Vegas and get it over with, but my husband had dreamed up some wedding with family, etc, so we did it. LOL
That being said, I would sit down with the bride like on a double date night, if you are semi-close to her, and just make mention about how gorgeous the wedding was and about how great friends they are to get the entire wedding party to take all that time off work, pay for all of the incidentals AND then give them gifts.
I expected nothing. If I received a card, I was happy. In fact, I'm such a minimalist, an empty card would have been better than some of the stuff I received. LOL The gifts actually showed me who knew me/us best.
I always give at least $50....no matter what. When you RSVP to a wedding, people have to take all of those expenditures into account before you/they decide to attend. I do the same with baby showers and usually just send a great gift.