My most comfortable dress pumps (low-ish heels) are ECCO brand, but I'd say you'd need to try some on before buying, as I think their sizing is a wee bit different.
Here's a link to a bunch on Zappos - and while they're not under $100 - you can often find them on sale at department stores, Amazon and so on. These may not be 'sassy' enough, but they're definitely comfortable:
http://www.zappos.com/search/b.....arity/asc/
Sometimes there are slightly lower prices for these on Amazon.
These look kind of neat - in the plum:
http://www.zappos.com/n/p/p/7553828/c/203220.html
Not as nice-looking as the Sam Edelmans that Maya posted though.
editing to add: I have shoes that are 7.5 and 8's as well - it seems to depend on the brand. In the ECCO brand, I take a Euro 38, and it fits perfectly and comfortably.