How to straighten my hair without a straightener? Product ideas?

I am so sick of my hair. It is thick, wavy and gets frizzy too often and I wish I just had straight hair. When I get out of the shower it takes about an hour to blow dry and straighten my hair and sometimes I just don’t have the time that I have to skip washing my hair (multiple days in a row) and then it just feels gross. What are the best products out there (i.e, conditions, or anything) that I can use so when I get out of the shower I can let it just air dry without having to worry about it frizzing up like a white girl afro or put something in it after the shower to prevent this? I’m looking more for hair relaxers, not gels to keep it in place. I heard about Keratin, but I just don’t know where to start and I don’t want to waste a ton of money. Any ideas? Please help!