Baby shower etiquette

Any advice would be appreciated! Coworkers are throwing me a shower at work on Wednesday. Instead of buying gifts off of my registry, we're doing a donation toward a mamaroo swing. People donate if they want to and then sign one card.  How do I do thank you cards? I work in a large school so this could mean potentially 60ish cards and I'm already 38 weeks. Is one thank you card that I leave in the office tacky? Most people give $5-$10 for these types of things so I'd feel like I'm maybe going overboard if I write each person a personalized thank you. Just want to make sure I'm thanking them appropriately because I really do appreciate it!