Mother's Day was likely created to keep florists in business.
Father's Day may very well have the same effect on gun parts retailers (probably motorsports and hardware stores too).

The e-mail traffic related to all the Father's Day deals is fairly overwhelming, but there are some noteworthy deals.

Primary Arms has their Father's Day sale going on and they keep on adding stuff to it. https://alnk.to/b7y1pwt

Several things are noteworthy, like this Del-Ton upper for $210: https://alnk.to/ge5ZR8g
I do not like government profile barrels, plastic handguards and fixed front sights. However, a complete upper with a BCG for barely over two hundred is a very good deal.

Palmetto has their Father's Day sales up as well: https://alnk.to/aANKBwI
You can get a basic complete AR lower from them for $119: https://alnk.to/6bUO5ad

Combine it with the upper from Del-Ton above and you have a fully functional AR-15 for $330. Just add a red dot sight and you are ready to go. For example, you can pick up Sig Romeo5 for $119 from Palmetto: https://alnk.to/3J6clRL
Since, there is a fixed front sight on this rifle, let's add a rear sight for a tiny bit of redundancy: https://alnk.to/cHMQnxK ($56)

What you have, then, is a very basic M4orgery with a red dot and co-witnessed irons for $500 plus tax, shipping and DROS. That can vary based on location, but you are likely under $600 altogether.

Everytime I see something like this, I always think back to our rack rifle discussion (hat tip to @TheMarksman ). Is this how I would build if starting from scratch and having a bit more budget? No. However, at this price, I am always tempted to pick up a couple, sight them in and shove them into the back corner of the safe "just in case". For me, it is even more appealing in that I have plenty of red dots, rear sights, carbine stock and pistol grips laying around left over from previous projects.

For my own personal preferences, I did just pick up a couple of Reptilia grips https://alnk.to/31rarCm and another Reptilia Recce-E stock from PA https://alnk.to/3ybro3y since they are discounted.

With AR grips, I keep on going back and forth between the Kungfu grip from DFC https://diefree.com/kung-fu-grip/ and Reptilia grip. I like them both despite the somewhat different fit and they seem to do better on different guns. I am going to set-up two nearly identical ARs with these two grips and see if I can narrow down the differences.

Opticsplanet has their Father's Day thing going on as well, but they do it as a coupon code. DAD35 gets you $35 off on anything over $300 (DAD25 for anything over $200 and DAD15 for anything over $100). For example, it is a bit of a discount on the Element 5x30 that I like. I think they have a next batch shipment in the US. https://shrsl.com/4j1i0 They also have 70gr TSX 5.56 ammo we recently discussed in stock. It is not clear to me if you can use the discount code twice for two different orders, but it may be worth checking. I used one of the coupon codes and it worked.

With Brownells, I am not seeing anything explicitly for Father's Day, but they have a good number of sales up on the website including 15% off on anything with Brownells brand to commemorate their 85th anniversary of doing business. https://alnk.to/4qLejFO

Taking a leasurely look through what else they have on sale, a couple of things stood out. If you want to try a doppler chronograph, they seem to be closing out the original Labradar for $350 https://alnk.to/90yVOTU I am mixed on this one, since I much prefer my FX True Ballistic, but it is a lot more than $350 https://alnk.to/dex7mv1
The new Garmin that everyone seems to really like is about https://alnk.to/hhAxVhv
I am sticking with the FX on the strength of it measuring multiple velocities out to 300 yards (real time BC truing), but if you just want to try a doppler chronograph... the original Labradar at a steep discount might not be a bad idea.
If you are looking for a simple inexpensive 30mm scope mount, Brownells one is $79 at the moment https://alnk.to/8tOESyt It is a decent mount, especially if you use a little grease on the diagonal surfaces of the rail when you mount it. Alternatively, they also offer the same mount bundled with Burris RT-6 for $369 total https://alnk.to/3ngGqVF
They also carry Swampfox Tomahawk II 1-4x24 that I am currently testing https://alnk.to/dLhoqx3, but I do not see any specific discounts.