It's never that straightforward. The way it works is: Company A wants to sell its wares to IAF. So they hire a lobbying firm. Now this firm also employs retired Indian army-men and retired MoD personnel who still have "connections." So they get their pay from the firm, while putting in a good word for the weapons system. Ultimately a price is quoted, but that price includes the fees paid to the lobbying firm, along with the profits to the manufacturer. That is why the cost of each Apache helicopter comes to 155 million. The actual manufacturing cost is far less.
I have nothing against the Apache; it's a fine machine. But when you deploy a heavy chopper like the Apache at high altitude, its weapons-load becomes very less, because its engines lose power at high altitude. THAT is the current problem with the Apache deployment in Ladakh. Sure you can deploy it, but it will only carry 1 rocket pod and 2 missiles, because it was not designed from scratch for operating in high altitudes.
The LCH can actually carry more than the Apache when operating at higher altitudes, because it was designed to do that. And yet even the LSP order for the LCH has not been finalized yet. They ordered an imported air-to-air missile for the Rudra and LCH, why couldn't the MoD/army also order a foreign ATGM as a stopgap?
About the Helina/Dhruvastra: The Helina would've worked fine in Ladakh but was rejected after a trial in Jaisalmer in which its first iteration seeker missed 1 out 3 targets. And that was in the hottest month in Rajasthan where they tested it against a camouflaged target with its engines off and sitting out in the desert sun for a long time so that the target was the exact same temperature as the desert around it. All foreign ATGM with IIR seekers of that generation would also have had trouble against such a target, because IIR seekers do not do well in such a high heat situation. Instead of rejecting it outright, the MoD/army could've accepted it in a limited role for high altitude areas, while the DRDO worked to improve the seeker for the desert. The Dhruvastra, the follow-up to the Helina, has an improved higher resolution seeker which works fine in the desert camouflaged situation.