I'm level 55 and the Arch Mage. Where can I get high level Destruction spells?

At college of winterhold for sale from various trainers. They scale with your skill level, so you must have high enough skills before they are available for sale. Otherwise you just have to go dungeon dwelling and hope for the best.

My Destruction skill is 72.

Check this out for more info.

http://elderscrolls.wikia.com/wiki/Destruction_(Skyrim)

Thanks.

your skills in that school of magic got to be 90 or 100 and then you have to do a quest for them to sell the master spells for that school of magic.

I want that fire spell that's in the first trailer. Where the player hits the ground and causes a big fire explosion.

You'll need to get your destruction skill to 100 (maybe 90?) then do the master destruction spells quest from Faralda.

I read that it's at skill level 100 for Destruction and not 90 like for the others.

Ji Soo posted that Wiki link that shows the spells and what levels you get them at, it was actually really helpful. Makes me rethink how and what I cast.

do you need to be a member of the college if you, for example wanted the master conjuration spells?

Get to 100 in destruction and then talk to this one lady made( the one who sells destruction stuff) she will give you a book and you have to bring the book to different locations and do stuff with it. Then you'll get the spell your looking for and now she will sell the master ice and lightning spells. I think most master spells come from a quest from the mages who master that type magic.