Yep Duncan has a few “butterfly” models. The cheapest butterfly is just called a Duncan butterfly. The xt is an upgraded version that uses a bearing. There are a few other versions as well (aluminum, micro, etc) but for your uses a simple Duncan butterfly is what your looking for they are usually 5 bucks at your local target or heck I’ve seen them at Cracker Barrel. Yye doesn’t sell the fixed axle version but if you want to buy online that rainforest named site has them cheap.
Do note there are new and old molds the newer mold is more solid than the older but they both work fine.
New
Old
This is what you’re looking for just pick your favorite color. Purple and pink are exclusive to certain stores
Also check this thread out Butterfly Hype-Beasts Thread 🦋 - More colours and special editions?