I'm a deal expert and these are the best 4th July mattress sales for 2023 — by bed size

Zinus Green Tea Memory Foam Mattress | $169 $123 for a Twin (save $46)
This is the most reasonable (and comfortable) mattress we've reviewed that's on sale for the 4th of July RN. In our review we rave about its motion isolation, though be aware that it's best for side or back sleepers. It comes with a 100-night trial and you can choose from four depths from 6 inches to 12 inches. Do bear in mind it doesn't have great edge support but the fact it's made with green tea neutralizes odors. 

Siena Memory Foam Full Mattress | $349 $649 (save $300)
Included comes free shipping and a 180-night trial in case you don't like this Full mattress (you will!). I'ts rated 6.5 on their firmness scale, with 10 being super firm. We rated it 4.5 stars in our review as it offered good spine support and it was gentle on pressure points. It's also great for all types of sleepers. For $649, it's a steal, plus if you pay an extra $99 you can get a mattress protector, sheets, and two pillows include, too.

Nectar Mattress | $1,049 $699 (save $350)
If you're a memory foam lover, then this mattress is for you. It's medium to firm on the scale and in our review, we gave it five stars and claimed it's great for all types of sleepers. It comes with a 365-night trial and similar to the Siena, pay $159 and you'll get two pillows, a sheet set and a protector thrown in, too.