I'm not trying to start a war either, even though my language is strong, I am simply trying to point out the crux of the issue, which is what and how it was put by sleev, and explain the reasons for the reaction.
If you have the intentions of doing this, tell the shopworker who is fitting you for boots and gauge their reaction.
Oh of course. I wouldn't just go try on boots for an hour and be like "Well I like them, but they're cheaper online so bye" haha. I would definitely tell them before hand.
But anyway, back to the original topic, I'd be ok with getting the size I tried on even though it's a different boot?
.....and OP, I'm not saying to sit in a shop either and waste their time, but its hypocritical at the same time to say try something on, but spend more money just because its a local shop... Too many people get butthurt on the net from text. Snowklinger, I'm not even judging your opinion, but you have to be able to get what you want at a reasonable price. Trust me, whether you want to believe me or not, every board I've bought has been from my shop and all but one set of bindings and one set of boots has been bought at the same shops. I even tell them I'd rather support my local business when we talk. The ethics and moral issue is to not be a habitual douchebag as you put it, but for the sake of OP's thread, jumping in this time, trying on a boot tactfully and saving a couple bucks isn't unethical or morally wrong. If a shop is willing to help the OP this time, OP is more apt to go and buy more gear from them because they were courteous. I've used these practices before. Its caring about your customer and assuming certain risks in a business. I'm going to stop the debate at this point and we all share the same love for this sport.
As ETM said, I missed the part that you tried on a 32 boot. You should be ok. Like I said too, you can verify there is a reasonable exchange policy with the site you are looking at to make sure you can exchange for a different size if it is off.