Route53 does support wildcards (from the Route53 FAQ):
Q. Does Amazon Route 53 support wildcard entries? If so, what record
types support them?
Yes. To make it even easier for you to configure DNS settings for your
domain, Amazon Route 53 supports wildcard entries for all record
types, except NS records. A wildcard entry is a record in a DNS zone
that will match requests for any domain name based on the
configuration you set. For example, a wildcard DNS record such as
*.example.com will match queries for www.example.com and subdomain.example.com.
You will need to obtain a wildcard SSL certificate separately and host it on any servers accepting these requests.