Can you find just about anything in Thailand cheap?

I am traveling to Thailand this summer for volunteering and I know there are lots of night markets in bangkok and all over. I guess i was wondering what type of stuff you can find there. Such as there are many things that i want that are way to expensive for me to afford, such as an ipod or some other mp3 player device, and b guitar, and just for fun though i usually dont give a **** about designer brands a le sport sac bag. I was wondering if i can find all these things in markets. Now i know that it wont be a "real" ipod i dont know if its not even that brand name, just some sort of mp3 device, and for the purse i dont even care if its a rip off. Also i am not going for shopping its just a perk of being there. Anyways this has turned into a rant, please repsond, thanks so much