I wonder because I have a more than $10k in my engine and that's from [years] ago.
$7K for an engine and swapping out the rotating assy in an already machined 4-bolt, cast block...

Hmmm...
What's cost out-the-door from "The reputable engine builders"?
Back in 2014 I had my race engine built.
8.2" deck
Dart Iron Eagle Block
At that time 358 cid (3.4 X 4.090)
Callies crank
Oliver rods
JE coated pistons (9.2:1)
AFR Renegade 220 heads
Jesel shaft mount rockers
Jesel belt drive
Custom solid roller cam
Canton kick-out oil pan
Obviously zero balance, ATI damper, double key on the crank
Assembled long block was right at $25K
Fast forward to 2020 (cliff notes)
Take to local machine shop for refresh.
Bored to 363 cid (3.4 X 4.125)
Asked for 11.0:1
New JE coated pistons, installed with standard duty pins, not the severe duty pins like the original pistons had
Turns out compression was 10.2:1
"Comp valve grind" Never touched the valves, just new springs.
Asked for new oil pump, oil pump reused.
Asked for new SFI flex plate, said he could not find one. (I bought one from Sumitt Racing next day)
They stripped out a head bolt hole in the block, had to take it back to get it repaired. (Helicoil)
Bill was $6,200
Obviously not happy.
Take engine to a different machine shop 70 miles away
Have engine inspected.
Cylinder bores have LOTS of taper
End up taking the block out to 4.135 (now 365 cid)
New coated pistons (again)
Correct pins, correct 11.0:1 compression
Pistons are from Diamond, getting parts during the Covid Hoax is a problem. Takes over 1 year at this shop to complete everything.
Obviously new balance job, add getting camshaft double pinned.
Cylinder head inspection results in finding a crack in a intake runner to coolant passage.
New AFR Renegade heads (heads as delivered did not have HD valves)
New valves, Stainless Intake, Inconel exhaust,
Bill out the door $10K
Self inflicted gunshot wound:
Decide to change from FAST XFI to Holley Dominator
Decide to change to Coil Near Plug Ignition.
Add $4,500
All of this for a "refresh"
Lol.
Your results may vary...