There are a bunch of at-home alternatives to salon keratin treatments, although none of them are going to give you the same effect as the Brazilian Blowout. Luckily, they also aren't going to give you the formaldehyde of the original, either.
If you want a month of moderate straightening and glossing, look into Liquid Keratin 30 Day Straight. It's not a relaxer at all—it basically just cuts down on frizz and makes it easier to straighten your hair (or wave it, if you want).
The Lasio Rio de Keratin Cocolada Keratin Treatment bills itself as the more “natural' version of at-home protein infusers, and it contains a bunch of coconut oil and Vitamin E to hydrate. It lasts up to a month, but repeating it every other week seems to be the standard. Mostly, we like it because it's gentle and comes in one easy-to-use starter kit.
If a few weeks of protein-coated hair seems like a lot, you could also try Keratin Complex Straight Day Styling Spray. It's exactly what it sounds like: styling spray that covers your hair in keratin and then washes out. Good for heat styling protection and for people who are wondering whether keratin will do much of anything for their hair.