Keep in mind that most N64 USB adapters don't support the Rumble Pak. There was a inexpensive adapter with rumble support called Adaptoid around ten years ago, but the company went under and all Adaptoid prices have skyrocketed. A more affordable alternative is from
Raphnet, which can customise their USB adapters to virtually any console. I have a combined N64/GC adapter with rumble support. Even though I don't have a GC controller yet, I like to keep that option open in the future. Otherwise, there are plenty of cheapo adapters on eBay without rumble support.