Don't get too discouraged. I know it's very frustrating when it seems like nothing works for your hair. It just requires a bit of trial and error. I recently started using Hollywood Beauty Olive Cream. It's very moisturizing (for me anyway), and it's cheap. Only around $3 and you can get it anywhere like Walgreens or CVS. I also recently found that I have to use something heavy on my ends because they get dry so quickly, so I've been using shea butter mixed with olive oil (just regular extra virgin olive oil, not the cream I mentioned above). I had a hard time finding an oil that my hair really likes, but olive oil seems to work well for me. It's the only oil that my hair seems to "drink." Just use a little though to prevent greasiness.
Lastly, I spray my hair a lot. At least 2 to 3 times a day. Always in the morning when I get up, always at night before I go to bed, and often once or twice throughout the day. Since I have hard water at home, I use distilled water for my spray (or a moisturizing spray that I bought called Soft & Precious if I have that on hand). I used to think something was wrong if I had to spray my hair that much just to keep moisture in it. But now I look at it like this, I have kinky (I guess it's 4b) hair, and kinky hair gets dry and thirsty. That's just how it is. If I feel myself get physically thirsty throughout the day, then I think nothing of drinking more water to quench my thirst (drinking more water, by the way, has helped with my dry hair as well). It only makes sense to do the same for my hair. Sorry this was so long, but I hope you found some of the info helpful in some way.