I have a AT&T Avail right now, with the original sim card on the $25 montly. I wanted to carry that over to my newly ordered samsung galaxy express, but soon realizing that the galaxy uses micro sims instead of the old sim cards. Is it possible that I get a new micro sim for my old account that I am currently using? If so, how much?
Yes, you should be able to get a new microSIM to use with your new phone. Sometimes there is no charge for them if you go to an AT&T corporate store, but they may run you up to $25. Of course, there are cheaper alternatives such as eBay or Amazon where you can find them for under $5 as well. I would recommend going to a store to have everything carry over to the new SIM.
You could also trim down your current SIM using a microSIM cutter (also on eBay) or a pair of scissors. You would have to be VERY careful if you were to use scissors. Personally, I didn't trust myself enough so I went ahead and bought myself a microSIM cutter. Didn't cost more than a couple bucks.