Assuming that you're flying from IAD and thinking of using the new route that MaxJet is supposedly about to start, then sadiqhassan has identified the reasonable non-stop alternatives to London. Those premium economy flights might cost you less than MaxJet considering that you're trying to buy them in the US, where they're often very keenly priced. But they are premium economy, not business class, whereas MaxJet will at least provide a business class seat even if it's not state-of-the-art stuff but one or generations old.

I suspect that the question you'd like answered is "Should you buy MaxJet tickets?" I wouldn't dare to answer that, but if I asked myself the question "Would I buy MaxJet tickets?", I'd personally answer that with an immediate "No" - not for travel 6 months away. There's many a slip 'twixt cup and lip. Even if MaxJet itself were to survive until August there's no corresponding guarantee that the IAD route would survive that long. LON-WAS is a different market from LON-NYC.

If I made that choice myself, I might be proved wrong and have missed out on a bargain if MaxJet survives that long. But the other side of the coin is the hassle of trying to get my money back if MaxJet goes under, plus the hassle of then trying to make alternative arrangements when cheap tickets might be more difficult to come by.

However, that's all a very personal take on the dilemma.