I have some of the Pro series cabinets, and like them quite a bit. Whichever series you get, shop around for them. I got mine from GarageAppeal.com; I'd recommend calling them, especially if the "package deals" from Costco, et. al., don't exactly fit the bill. GarageAppeal.com may let you design your own package, with a discount off the ala carte pricing depending on how big your order is.
When I was shopping, Costco did have a deal for a "4-pack" of wall cabinets, and that was a the best deal around for those.
Somebody else recently got theirs from Overstock. I found Overstock's NewAge pricing to be way high, but maybe they adjusted.
Obviously consider shipping costs and sales taxes too--depending on where you are, that can have a significant effect. Speaking of shipping, avoid ordering cabinets one at a time, especially the wall cabinets. They are not packed to withstand Fedex/UPS/USPS. A bigger batch, strapped to a pallet and shipped via truck, is a better bet to get there intact.