Good question Ryan. I think there are a number of things that come into play.
A bale of straw can vary a lot in price but around here it ranges from about $ 5.00 to $ 10.00. I would guess about $ 6-7.00 would be typical. A bale of straw will cover about 500 sq. ft. So material cost would be about $ 13.00 per thousand +/-
The other thing to keep in mind is when hydro seeding you are doing the seed, mulch, fertilizer and tack in one shot. When you are blowing straw it is a separate step. Straw will also often need to be raked off one the grass is growing.
The flip side of that is with a good straw blower it is pretty fast and you don't have to fill with water.
As far as results go a few years ago I did some seeding at a Sysco warehouse. I did one big area then they did some smaller areas with seed and straw and had me come back and hydro seed a few small areas a few days after they did the seeding with straw. When I checked back the small areas I hydroseeded were far better, thicker and taller than the areas they strawed. I have also hydro seeded a number of jobs where they seeded and strawed with no results or poor results and they came out well. I have done dozens of jobs like that so I do think in general hydro seeding has better results than seeding and strawing.
I do think straw over hydroseeding can be a good thing in the hottest part of summer or very early in the season. I think the straw can provide shade that helps preserve moisture and in the early part of the year can help keep the soil warm.