http://cgi.ebay.com/16-Guest-Baby-Shower-Party-Pack-Plates-Cups-Napkins_W0QQitemZ180283298590QQihZ008QQcategoryZ102430QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
http://cgi.ebay.com/Mod-Mom-Baby-Shower-Plates-Banner-Invites-w-Envelope_W0QQitemZ180283282505QQihZ008QQcategoryZ104195QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
Here are some on ebay, they have a mom holding an umbrella? seems to be a mod mom theme...dont know if this helps?
oh, i forgot--with the price of the umbrella themed plates, we bought the "pretty plates" for the cake only, and then bought just everyday colored plates for the food.....that way, the cake/gift table was all done in the theme, although everything else was just matching colors....maybe that'd make the burden less, esp since people will eat food, then throw away the plate, rather than use it again lol.....
IDK if you guys have 99cent stores or dollar trees up there, but often times you can find stuff like that there, or big lots...where did you find your invites? otherwise, you might have to pick up the blues and such in the stuff you did find....or, if you or someone else you know can draw, you might be able to redraw the invite, and take it to a local printer, and see if they could do it, even if it's just napkins.....the rain slicker theme to match might not be too bad, but i guess it depends on if you can incorporate it....
i know all my stuff is like baby jungle animals(monkeys, lions, hippos etc), and even though we found the cups/plates and napkins in dollar tree austin, i got lucky and found the table cloth, banner, and gift baggies at my 99 cent store down here in houston.....but for my invites, i found @ dollar tree printer paper that had the same characters, but with brighter colors, and paid $1 for 40 "invitations" lol....and then $6 at staples for the envelopes.....but i'm having kind of the same problem you are, with my girlfriends shower, b/c i'm hoping to do a "beach baby" theme.....and i can't hardly find anything lol.....so me, her nurses, and another friend are pretty much going to put it all together by hand....good luck though!!!!!