OP here.
There was registry information in the invitation, so they are expecting gift.
The event is at a place I did not recognize, so I do not know if it's a hall or a spa, but definitely not in someone's home. There was zero information about cost/expectations/etc.
If this was for a traditional wedding, I would be confused, but would just accept or decline upon further information.
Some of you seem to think I'm to rigid, but I thought shower guests were supposed to be invited to a wedding. AT least, that's what I've read on every bridal etiquette site. This is not a destination wedding I cannot attend, I am being told I am NOT invited and they MIGHT choose to have a local reception later. I equate this to an elopement - part of that choice is giving up some of the trappings of a traditional wedding. It just seems convenient to me - you don't want to host others for your wedding, but you still want to be showered with gifts.
ETA - if this was a spa day for the bride to spend time getting pampers with the women in her life, I would think it was a fabulous idea. It's the shower addition that doesn't sit well with me, especially since I had to find out through back channels that a wedding invite would not be forthcoming. I would have assumed it was based on the shower invite.
Op after reading my way around EHell, I thought the same as you. That events about the wedding, including showers should include people who are actually invited to the wedding.
As you said, it's not like it's a wedding you cannot attend. You haven't been given the option to attend!
I read a post on here a while ago in relation to a destination wedding that said something like "if i'm not close enough to be invited to the wedding (which is the main part of the gig) why would I want to come to the party to celebrate the wedding I wasn't invited to, and bring a gift no less." I think the same about showers and receptions later.
Also it's not a reception later. It's a party celebrating their wedding - that you weren't invited to and you're probably expected to bring a gift to.
But then I guess that opens up a whole other can of worms. Is the gift you're expected to give at the reception later, a gift because they got married - which I don't like, since you weren't allowed to be there to watch them get married, or is it a gift thanking them for their hospitality of the party (reception)? If so, then don't put together a registry, because I don't need advice on how to give you bottle of wine to so thanks - but now i think i went overboard!
Anyway Op, given you don't know this bride well, I feel the same as you!