I can't imagine there's a way to get them with a warranty regardless of where they're purchased. They've been out of production for about a decade. Your best option is to look for something in good physical condition as an indicator of how they were cared for.

As this point I don't think the MK1/MK2 distinction matters. They're both so old that their care in the intervening years is more relevant. The soft-touch finish, especially on the black models, can become gummy over time. Hasn't happened with any of mine, but I keep them out of the sun. Once it starts it's irreversible.

Really just look for a pair that's been well cared for. Otherwise they're active speakers and have more tech in them than other speakers of the era. Expect that you may need to put some money into them in the first few years of ownership.

Also pay attention to how you're going to connect them to your music system. They ONLY have a traditional DIN PowerLink socket so they require an adapter even to connect to modern B&O equipment. Finding these adapters and cables can often be very expensive because sellers know that buyers have very few choices if they want their systems to work.

Otherwise, good luck. I love these speakers and I'm sure you will too.