These are the best Prime Day deals under $100, from smartwatches to LifeStraws. Be sure to check out our full list of the Best Prime Day Deals and find highlights in our Prime Day liveblog. Photograph: Kat Merck Jisulife Handheld Mini Fan $15 $13 (13% off) Amazon Handheld fans are everywhere for good reason. Photograph: Amazon Nalgene Sustain Tritan BPA-Free Water Bottle $17 $14 (18% off) Amazon $17 REI efore stainless steel and Hydro Flasks, there was the Nalgene. Photograph: Amazon Valtech Magna-Tiles $50 $35 (30% off) Amazon Magna-Tiles—beloved STEM toys—let kids build 2D/3D creations with magnetic shapes.