Inexpensive software bgp router that supports route tags?

[ispcolohost at gmail.com (David H)]

Hi all, I was wondering if anyone can recommend a software (preferable), or
hardware-based router with an API, that supports BGP with tags on
advertised routes?  I want to use it for a RTBH feed and having it in
software would make certain things easier to automate.  I tried
Quagga/Zebra but it doesn't support tags.  I see Mikrotik hardware routers
have an API, but I can't tell if the API supports adding BGP networks, so I
need to investigate that further.  I can go hardware if I have to, with
some ssh/expect scripts, but thought there may be other options that are
easier.

Thanks,

David