Mike, you should be able to look at the belly and tell if its going to be much different. Keep in mind that the commercial hogs are broadsides (essentially bred for bacon) and the heritage breeds don't always have idea bellies. If the belly looks good, consider the color of the lean (pale or red) and the thickness of the fat.
I've worked with Berkshire belly a few times now and it cost me double what commercial pork costs. I don't notice a whole lot of difference with bacon, so I reserve it for pancetta or roasting uncured.
You should notice some difference, and you need to weigh how important that is to you. For me, any difference from a supermarket product is worth paying for. If I'm going to go through the effort of producing something myself, I'm going to go the extra mile.
A part of cooking is psychological. Something that took effort will usually taste better. Why do you think restaurant menus often list where they sourced their ingredient? Whether we want to admit it or not, it means something to the flavor (even if it doesn't). Ever serve someone bbq and they ask you how long it cooked? You say something like 12 hours, and their eyes glaze over and they say something that sounds orgasmic. Its the idea that tastes good.
You should certainly splurge and try it once, its the only way you'll grow as a baconmaker.
