You can get the Ohlins for far less than $3K. The prices on the Ohlins Japan website are their version of MSRP. KTS is running a sale so they come in less than $2500.
The AST's, once you option out everything, are almost $4K. The Aragostas are essentially the same setup with their own spring, proprietary housing and coating. The internals use lots of AST parts which is why they can rebuild them right here in the states.
You can buy them at the below link, same place where you can get Aragostas. The one advantage I see to the Aragostas is the side adjuster on the rear. No need to drill holes to adjust the rear shocks. I know for some that isn't an issue but for anyone running a G37/Q60, it's a necessity due to no rear shock tower access up top.
Link:
https://www.kts-web.com/ec_shop/prod...roduct_id=8498
Personally, I'd go for the double adjustable Aragosta Type SS if I had to do it all over again and specify my own spring rate.
https://www.kts-web.com/ec_shop/prod...roduct_id=8752
Go here to contact them in English.
http://www.kts-web.com/overseas/contact/index.html
You'll need to give them the exact part number. They ship quickly if it isn't a holiday and their English is decent but not perfect. Various states have different importation fees. In Texas, it was like $50 total.