The high-end HF3520 comes packed with five different wake-up sounds, an FM radio, the ability to set two different alarms, and a color-shifting light that accurately mimics the gradually shifting light you’d see during a real sunrise. I’ve been using a cheaper model for years, and I miss is desperately whenever I travel.
The HF3510 is also available for $66 too, after clipping the $10 coupon on the product page. It lacks the 3520's colored sunrise simulation, meaning it only has one color of light, rather than shifting from red like a real sunrise, but it’s otherwise very similar to the 3520.
If you’re on a budget, the barebones HF3500 is still available for $40 (after clipping the $10 coupon), within $5 of an all-time low. This model doesn’t offer any kind of radio or natural wake-up sounds, just a standard beep, but I’ve owned it for years without complaint.