The milk seems like a great price. Plenty of land, guernsey's make some of the best milk.
Personally I don't think hiding anything from your spouse is a good idea. Maybe you can explain to him why it's so important, and then agree to disagree, and buy some at aldis and some at the farm?
As for taste, good raw milk tastes... like milk. Seriously, most people I know (including myself) agree that their first taste of raw milk tastes like milk, but more... intense, and milk-like and what milk should taste like. It's sort of... more concentrated or intense milk taste. Like the difference between a conventional vegetable and an heirloom vegetable. More nuance, more flavor, but it tastes the same, just more intense.