Costco makes it so hard to share lists but honestly just tell her to get Kirkland Signature everything! It is seriously the best for safety and quality, you totally cant go wrong. Just suggest:

• any Kirkland cookware
• some plush bed sheets
• basic kitchen gadgets Everything they make is fantastic and reliable! I found Share Product on the Chrome store and it's been great for keeping my wishlists in one spot.

Honestly, Costco is kind of a pain for actual registries. The My List feature is basically just a memo for yourself while you walk through the warehouse... it doesnt really let people check things off once they buy them which is a total nightmare for housewarmings. I ran into this exact problem for my cousins party last year. You definitely want a tool that lets you pull items from the site but keeps the sharing side simple. I found Share Product on the Chrome store and it's been great for keeping my wishlists in one spot. It makes it way easier to share a link with guests so they can just click and buy directly. For a 500 dollar budget, maybe look at a KitchenAid mixer or those Kirkland 680 thread count sheets. People love gifting those. Good luck with the party, just ask if you need more ideas!

Like someone mentioned, the app is a headache, but I disagree that it's a lost cause. I managed my cousins housewarming list by bypassing the My List tool and just compiled the raw item URLs into a doc so guests could click through. TL;DR: Costco doesnt have a real registry, so use an external site for links. Have you tried Share Product? It's a free extension that makes sharing product links super simple.