Is it too late to learn how to skateboard?

I'm 21 and a female. it's summer and I want to do something fun so I was thinking about possibly teaching myself how to skateboard with no help from anyone. I eventually want to teach myself how to do tricks but first i need to learn how to balance. what is some good advice to give to a beginner? I am very athletic and i'm not afraid to get hurt. i snowboard some times and i can balance pretty well and go down a normal sized hill without falling. i started watching these guys i used to go to school with but i never really talked to them. i want to learn to go down ramps and do kickflips and manuals and stuff. I know some skate lingo because I like playing the tony hawk skateboarding games and also the game skate lol. i just think it would be really fun. also, where is a good place to buy skateboards and about how much do they run? do I have to buy the board, wheels, and trucks separately? or can you buy skateboards that are already put together? and does it matter how long the board is if im a beginner or does it not matter? i would like a pretty decent board one that won't break but i don't want to spend like 200 dollars to put it all together..and if i practice at least 4 times a week do you think i'd be a pretty decent boarder by the end of the summer?