That ds phat looks like it hasn't been used much. To be honest, mine looks a whole lot worse than that. I find it very fishy that that ds is $30, and it makes me think that something is wrong with it, especially considering the state the ds is in, the person who is selling it could be asking much more.
Some major things to consider with the ds phat are these:
- It is a lot bulkier than a dslite (I actually liked that fact xD)
- The brightness settings are atrocious on the ds phat, it only has two settings: on and off. If you're lucky you might have one with dslite firmare on it. If you use a flashcart, you can actually access the brightness settings. It only works while using the flashcart though
- The battery life is worse than that of the dslite, especially if you have a phat with dslite firmware and you use the higher brightness settings
- The gba slot won't make gba cartridges stick out, however some slot-flashcarts are specifically made for the dslite, which has a smaller gba slot, therefore they won't fit in a ds phat
- The stylus is very bad, it's thin and flimsy. If you consider buying a phat, you might as well buy a set of styli for the dslite
- Most skins and cases are made for the dslite or dsi. Carry cases for the ds phat can be quite hard to find