Four Showers for First Baby

My sister and brother-in-law are expecting their first baby in the fall. I have been invited to four separate baby showers, three of which are out of town. I am throwing one of the showers with my mother. I am currently a graduate student with significant student loans, so money is always a concern for me. How many of these showers am I expected to attend? As a sibling, am I am expected to attend/send a gift to each shower I am invited to or is it sufficient to attend the shower I am co-hosting?