I thought there were two different prices for two different sized lockers. I believe the smaller locker was $5 including the $2 deposit and I believe the larger locker was $7 including a $2 deposit. (However, I could be totally wrong! I'm trying to recall...)
As for the sizing of the lockers, it depends on the park. I recall that Epcot only had the larger lockers, Magic Kingdom had the larger lockers, MGM only had smaller lockers, and AK had both.
I know I just went in March/April, but it's so easy to forget!
Also, the lockers are yours to use all day. My friend and I each packed a back pack with sun tan lotion, a jacket, etc. and a few days did go back and get our items from our lockers. We did ship our purchases to our resort, too, but, of course, on the last day, we kept them and stored them in our locker.
Have a wonderful trip!
