I know you have pretty much decided on your speakers but have you considered buying FS? They will help you as you can buy subs as the last thing as these will have enough bass and you can later add the center and surrounds and subs. Lets say your 50K is a hard limit, are you open to something used?If you are you can perhaps buy 'something like this' -
https://www.hifivision.com/threads/polk-audio-tsi-500-for-sale.85209/. You might not even have to upgrade your fronts later.
For the AVRs you can perhaps look at something in the used market like these -
Dear FMs, This Marantz SR6008 AV Receiver has been my daily driver for last 7 years in a 5.1 channel home theater (B&W 685/HTM62 LCR, DefTech ProMonitor 1000 Rear). After I switched to pure 2 channel audio last October, I have strongly deliberated keeping it for a secondary music listening...
www.hifivision.com
Up for sale is my well maintained HT setup. Ask Price 1. Yamaha RX V375 AVR : Rs. 22,000 2. Sonodyne Sonus 1501v3 bookshelf speaker pair : Rs. 13,800 3. Sonodyne Roarr 108 Subwoofer : Rs. 18,000 Location : Mumbai / Thane Shipping extra at buyers risk. Would prefer local buyer. Age : 6 years...
www.hifivision.com
PLEASE NOTE -
********* I have no affiliation with the sellers nor am I endorsing the products in the posted links. These are just for reference for an alternate way to go about it - obviously you should audition if possible.
********** I know used goods carry a huge risk as they are almost always out of warranty and it is a lot about luck, but I have personally used many in the past and always got something worth a lot more for a lot less including my first HT setup and my first stereo setup which I used for years. It is one way to go about it and you can always upgrade what you do not like later.
********* The AVR might be worth investing in new, as that will get you all the latest features like eARC or Dolby Vision etc, BUT if you do not need those, consider something used.