I have a portable "anvil" that was given to me a long time ago. It was old back then. In essence, it is a length of 6" well casing welded to a cast iron flanged base, and the top is a thick cast steel head that fits over the casing. The head is removable so that you can fill it with sand or whatever is handy when you get it to the work site, and so that you can empty it after you're done. This gives it substantial weight, and it keeps it a bit quiet, although it still has an excellent ring to it. There are handles attached to the casing. The whole thing is very manageable to move around, at least when empty.
The only two drawbacks as far as I can see are that it has no horn, and no hardie or pritchel holes. Since I rarely do anything other than small stuff, it suits my needs quite well. I haven't got time to employ all of the tools that I already have, so I figure going out and buying more would be impractical for me, especially an anvil. Maybe it would be sufficient for you, at least for a time?