Don't go into a shop and waste a boot-fitter's time. If a fitter spends the time and fits you correctly, support that shop; don't be a joey and get the boot online because you are cheap. The shop will give you a deal on the fitting (usually some kind of fit guarantee where they will take care of fit issues down the road). If you don't want to pay shop pricing (which is not a 30% markup by the way), fine- just don't go to a shop at all then. Part of what you are paying for is the service to help you find the correct fit.
I've got no problem with people trying on boots to get an idea of the fit and leaving- but return to the shop when you have the money. Sometimes, you live in the middle of nowhere and you can only get boots online, I get that too. But don't go into a reputable shop, have a legit fitter spend good time on you to find you the right boot, only then to not support the very shop that tried to take care of you. Support your local shops.