The general BF consensus on that case seems to be to get the more expensive one, and then stick with the same chain until both the chain and cassette (and perhaps even the chainrings) must be replaced. Sure, it costs more to replace the cassette and possibly also chainring, but by that time you would have bought 3-5 chains.
I've never been able to do this, because you must endure a period of mediocre shifting. But it makes sense, money-wise to do this.
Another thing you can do is be a neat-freak about your chain. Clean & lube it every week.