IMHO,
The cheapest led would be the CXA at >$100 per 60 watts more or less. (not counting labor)
That would be 1.6 dollars a watt.
A gavita would come in at 50 cents a watt, again more or less.(not counting bulb replacment)
The difference is I can run my trays as 27 watts a sq foot vs 50 watts...