The presence of leaders like Sardar Patel is what made India such a strong political unit, with undivided unity to the nation state, instead of multiple loyalties and power centers. Professing an ideological commitment is very different from nation building, and that is what made the difference between India and Pakistan post independence. Why democratic institutions flourished in India despite such ethnic and cultural and linguistic and religious diversity. But not in Pakistan, where a state religion was expected to unify the nation. Throughout the independence movement, we had freedom fighters who traversed the length and breadth of the country, and political parties (national or state level) that sprung from the native soil. People's power was represented through politicians and elected representatives, and not through the barrel of a gun.
Post independence, for the first time in centuries/millennia, the citizens of all the hundreds of princely states gave up their old allegiance to their kingdoms, and adopted a new allegiance to their state and country. Rajputs and marathas and nizams and nawabs all decided to live as one political unit. That is a major accomplishment, perhaps unparalleled anywhere else in the world, given the sort of diversity we have. Sardar patel personally went from king to king, giving them an offer they could not refuse - integrate peacefully with a nice retirement pension, or be annexed forcefully by the Indian army. All the kings and princes knew better than to resist the changing times, or battle the new idea who's time had come - a united republic, as opposed to archaic monarchies.
Besides, he modeled a system of pan-Indian government service, which we still follow today. (The IAF, IFS and IPS.) That, among other similar measures, helped forged a, overarching, pan-Indian identity.
Only a few people on earth can boast the accomplishments of Sardar Patel.
But that being said, 300 million dollars is a helluva lot of taxpayers' money to be spent in building a statue. A better tribute to him would be to build a power plant or hydroelectric dam or hospital or industrial unit or university in his name, which enriches the country further, and is not a monetarily unproductive asset.