"Enquiry" instead of "Purchase"

Hi,

Yes. Don't set any price in your products. On the frontend, instead of the price of the product, you'll see the text "free", which you can change with a translation override to "current price will be announced after the request":
www.hikashop.com/download/languages.html#modify
Also, make sure that the "display add to cart button for free products" setting is turned on in the HikaShop configuration so that the users can add the products to their cart.
That's basically it.
At the end of the checkout, the user will see the thank you page, and you'll be notified of the order by email.
You can then add the prices in the order.
You also want to check the order statuses in the menu System>Order statuses. Under the column "unpaid" you can enable the statuses for which you want the customer to be able to pay the order.
Then, change the status of the order to one of the statuses enabled in that unpaid column, and check the "notification to user" checkbox. The customer will receive the "order status notification" email which will automatically contain a link for the payment if you activate the "Payment of orders not paid immediately" setting of the HikaShop configuration.

This solution works fine. If you find a problem while doing it, please report what you did and when should be able to tell you what you're missing.