Found super clean 07 sti, but I need a real help!

[EJ20]

Hello guys

It's been awhile being without an impreza some may know sti is extremely rare in my country. Well today I found one for sale.
It's 07 EU spec sti has very clean body and has low mileage ( about 20k miles ) and owner wants to sell it. I offered him a $5k and he is kinda selling it to me. the car is 100% stock except for the boost controller

Spoke with the guy, and he is only 19 and he just got the car 2 months back, and had the boost controller installed and he know nothing about how much boost he was running there is no other mods even a boost gauge! (this is what I think killed it? maybe!)

Anyway, the engine/heads where killed 2 weeks ago. And Subaru dealer here has told him that replacing the engine costs $20k

if he said yes to my offer by tomorrow, then I need to import an ej257 long block. Seems my best option is to buy one from the us and ship it from there
Now I did some googling but all i see is these made by tomei and cosworth! Those are over kill for a stock car (and will remain stock for at least another 2 years)

Where is the best place to buy own sti long blocks? How much is average price for them?
I want to have a BRZ, but can't miss a $5K clean sti (thu its missing an engine ) If repairs is too much, then I guess I'll skip it and go for the BRZ.

thanks for reading