Good day,
i believe you did a mistake in budget: R350000,
anyways i could code it with pure javascript, with angularjs, backbonejs or reactjs, its up to you. it would be verry easy to incorporate in any type of page, because its gona be independent javascript plugin.
Also price depends on calculators, you did not posted any more details about it, so its hard to estimate on time and money.
im ready to answer any questions,
Kind regards,
Kestutis