Bridal shower gift question

Not sure where to post this so hopefully here is appropriate. My brother is getting married in May. I am having baby #2 in April and we have a DS who will be 2. I am a bridesmaid, my husband is a groomsman, and DS is a flower boy. We agreed to be in the wedding party before we found out I was pregnant but I still want to do it bc it’s my baby brother’s wedding. That’s just background to say we have already spent SO MUCH money on this wedding.

Future SIL’s bridal shower is coming up and I just took a look at the registry and am freaking out. Everything is over $200. We cannot afford this. We have a new baby coming and just moved for DHs job so we’re down to one income. SIL is a sweet girl but comes from a wealthy family and has no idea what things cost. I know I’m a bridesmaid but we just can’t afford an expensive shower gift on top of everything else.

My question is, do you think this gift is appropriate: two mugs, one with “good morning gorgeous” on it and one with “good morning handsome”, filled with their favourite coffee, the book A Good Girl’s Guide to Great Sex (SIL is a virgin and super nervous and she requested it) and a $30 gift card to the place they’re registered at. I’m worried about looking cheap and embarrassing the family since I’m his only sister and a lot of my side of the family can’t come but we probably can’t afford even that and I’m a hormonal mess right now. As a bridesmaid and her new SIL is this a tacky cheap gift?