There are two types of radiant barriers: Paint and foil. The paint is ghastly expensive - one of the best, Radiance E025 - is a bit less than $500 for five gallons. While it can be rolled on, or applied with a brush, the preferred method is an airless sprayer. That would be, for me, another $200 from Harbor Freight.
The other type is (a heavy) aluminum foil. The effective difference is 93% reflectivity for the foil vs. (best case) 75% for the paint. So then, the advantages of each are: Paint * Ease of installation
Foil * Price * Efficiency
I finally opted for the foil and got mine from www.atticfoil.com. I got 2,000 sq ft for $150 plus another $40 for sales tax and shipping. Two thousand feet will not be sufficient for my house (3000 sq ft floor space), but I'll be able to better estimate how much more I'll need. I plan to do the south and west sides first. I already owned an air compressor and staple gun, so no additional expense for another tool. I also own a manual staple gun, but I figured the pneumatic one would be easier.
The site mentioned above has bunches of videos on installing the material and comparisons with other products.
I'm not particularly looking forward to getting up before the sun this weekend, but I am excited about the savings in air conditioning costs.
I'll report back next week on the completion of the project.
Addendum: If you HAVE to work in a hot attic, here are a couple of tips to make the environment a tad more comfortable: * Put a lawn sprinkler on the roof to wash away all the icky heat. * Disconnect one of the attic a/c ducts and let it TRY to cool the attic. Don't forget to leave the stairway open so the air can circulate.