best recommendation you're going to get if you don't want to pay.
Unfortunately, even when using MIUI there isn't a "smooth" version of the ICS locker that really mimics the original (which is slightly annoying).
I think WidgetLocker might be quite smooth but as you say, it costs..... just depends how much you value an awesome lock screen
Use MIUI Locker -- and use the lockscreen downloaded here:
let me know if this was what you were looking for
EDIT again (lol):
Search for BlackIce 2.3 on Google, and download that MTZ file, closest you'll get to ICS lockscreen with added customisation you were looking for.
It's late and I'm going to bed otherwise would look out a link for you hehe