Amazon offers the Source Tactical WXP 2-Liter Hydration Reservoir System with Storm Valve in Black, model no. SO2050553, for $34. Clip the $10 off coupon on the product page to cut it to $24. Plus, Prime members bag free shipping. (Non-members can spend $35 or more to qualify for free shipping; otherwise, shipping costs $5.58.) That's $10 off list and the lowest total price we could find. It features a wide opening for easy filling, cleaning, draining, and ice insertion.

It's also available in 3-Liters for $25.62 after clipping the coupon.