Says 350 bucks for 100 feet.
Or can I just use regular PEX ? Can I just insulate it as it rises above the freeze line instead ?
You can use regular PEX below the frost line. You can also use cheaper ASTM D2239 sized polyethylene as is commonly used for lines coming in underground from wells. I don't know in practice if the poly can come into the house even an inch. I know that there can be some overboard interpretation of rules. With PEX, you could be OK at the house, even with nutsy interpretations. You could use copper to get outside of the house foundation, and then transition to poly.
Also note that insulation will not stop freezing. It will only slow freezing, unless you can keep a flow going. So there must be a source of heat, or the water should stay below the frost line, as it would with a freezeless yard hydrant.