Which bulb to get?

I am just about ready to put the plants into bloom.

And I am just about to purchase a 600 watt HPS system from HTG. The HTG site mentions that the bulb that comes with the system (the HTG brand bulb comes with the complete system) has "Increased Violet and Blue spectrum to enhance natural plant growth". I called HTG and the helpful person said that the HTG & Agromax bulbs have the blue "added" so that a person would not need to change their bulbs & could use just this 1 bulb for veg & bloom. He said that both the bulbs mentioned above are at about 3100k.

All that said, I am after a bulb which will be used JUST for bloom, what bulb from the HTG options listed below would be best? I have listed the extra cost per bulb to the complete system price. The choices are the HTG bulb @ 0 extra $; the Growbright 600 @ $8 more; the Agromax 600 @ $24 more; Sunmaster 600 @ $29 more and the Agromax 600 Hybrid @ $34 more.

Maybe I am worrying about nothing here but dropping the coin I am on the system I don't wish to make a poor choice of bulbs - but not break the bank in the process.

Here is the link to the HTG supply HPS bulbs: http://www.htgsupply.com/Category-High-Pressure-Sodium-HPS.asp

Thanks for the assist!!

I would just go with thier recommendations, if you are not going to veg your plants under a T-5 or a MH light before entering the flowering phase.

Good luck!