The cost savings really depends on what you want, your timeline, and any connections you have.
If you want all 2020 stuff and you want it now, buying a complete bike is probably your best bet.
If you are willing to wait, shop for deals, buy parts used or NOS, then you can probably save a decent chunk of change.
If they the Specialized you mentioned is AXS, you may have a harder time selling the Sram parts due to few people having AXS compatible wheels. (Not saying the parts won't sell, they just might not sell as quickly or at the price you want. And that is just an assumption on my part - I know I cannot just upgrade to AXS without replacing wheels.)