Try Disney store online. I bought some for our family a couple months ago when they were on sale. I got 4 of them for $23 including shipping they are super soft and seem to be great quality. I have washed them several times and have not noticed any sign of wear.
I just noticed that this site had a Hannah Montana towel and High School Musical towel on sale. (They had a lot of other fun things too, not all related to Disney.)
I bought my oversized beach towels at KMart last year. These aren't Disney themed, but they were nice and bright, and soooo plush (not the cheap kind at all - like close to the thickest softest towels we own) - they were Martha Stewart and $6. I've been eyeing them this year, waiting for them to come down for the end of summer.
We have a boat, so thick plush oversized towels are a must!