No don't do that. Look at the cost of the larger 600 and 1000 hps's on econolight, whatever their best deal is on one atm.
Last I checked $75-$100 or so max. You'll get more light and a better deal getting just one big light over four 150's.
Or buy a used ballast (ebay, craiglist) , and just buy a new bulb for it.
All around $100 or less.
150W: 15,000 lumens x 4 = 60,000 lumens total
1000w: 120,000 lumens total
Double the lumens, less or equal cost. 100% increase in lumens
600w: 90,000 lumens
30k lumens more than 4 150's, 50% increase in lumens