Various cities in Mexico meet your price limit, but there are enough problems in the country that I'd really carefully research specifics before I chose one.
One the other hand, I see Montreal at $381. Indeed a nippy time of year for them, but I've always found it a delightful city. They burrow in in the winter, and there is lots of underground public transport that can move you from place to place without ever going outside. And much going on inspite of the cold. Their marvelous ferris wheel runs 365 days a year.