There is no money rentability if You have project with multiple module RX TX and You buy it in shop.
One cost 20-30usd there is no calculation in price, better buy final and complete product, forget gaming with soldering and electronics, buy in shop market new and tested final product.
It must be DIY - homemade module.
There is no profitability if You buy that things, make yourself rx tx 433MHz RX TX.
I have project for heating house. Device controls all radiators in house, monitoring all rooms, and outdoor temperature with DS18B20, and controls each radiator (each room temp) based on predefined temp in PC software.
Each room have yours rx tx and base unit have one rx tx. 8 rooms 18 units RX TX x 20usd 360usd only for rx tx link.
This is not good. Because that I make my 433MHz rx tx link.