Drive by shower

My mother in law was super Adamant about helping with the shower... now they don’t even know if they’re coming... we didn’t budget to have to buy all the decorations so... I’m coming here to ask for cheap ideas on how to decorate. My mom went to party city yesterday and none of the prices online matched the prices in store... it’s Saturday so on line ordering isn’t really an option for us...

Update:: found out why everyone isn’t coming instead of telling me this and making me feel like they didn’t want too... everyone including my niece who was born two weeks ago have Covid.