Baby Shower Etiquette

My friend has offered to throw me a baby shower, which isn't really my thing but I thought it was lovely that someone has offered.

She kept coming up with loads of suggestions, such as hosting at a venue and having afternoon tea and posting proper invites. I prefer the idea of a low-key affair so it's changed to a few nibbles at my house. 

She's now trying to cut costs by asking guests to bring a plate and having my mum make the cupcakes. She's also said she's going to cost everything up and see whether she needs me to chip in. 

I sort of feel that if the cost is an issue, then she shouldn't have offered. And who did she expect to pay for the much more expensive first idea. 

I don't want to come across as being ungrateful but I didn't want this shower in the first place, now I'm expected to pay for it? And what costs so much anyway?!