There are plenty of aop frameworks for .Net but it seems that most of them are not that stable. If you really want to go AOP all the way, are willing to pay the money and can except that you get outgoing pings on compilations, then you should go for PostSharp (post-compilation).
I think dynamic proxy of Castle (runtime) is a very nice alternative and not that much slower actually.
https://github.com/KenVanGilbergen/ken.Spikes.Aspects
edit: Just added some testing with SheepAspect, works very nice.