Q: My purchases of Lion/Mountain Lion say no longer available in US store

They will only be available in the Purchases page of App Store for re-download.

I didn't say that.

Open App Store and log in with your Apple ID and password used to purchase Mountain Lion. Click on the Purchases icon in the toolbar. Scroll through your list of purchases to locate Mountain Lion entry. You should be able to download it from the button on the right side of the entry.

If you don't see them they may be hidden: Mac App Store- Hiding and unhiding purchases.

Otherwise, you will need to call Apple about getting a redemption coupon without having to re-purchase: Customer Service: Contacting Apple for support and service - this includes international calling numbers.

You can skip to Mountain Lion, but if you are going to do that, then why not just upgrade to Mavericks? The download is free.

You have access to the App Store and were running Mountain Lion. If your computer has the specs for Mountain Lion, then it can run Mavericks.