Since everything has some effect, it's hard to predict, in the abstract, which will make the most positive difference in your system:
I'm not a naysayer to power conditioning, but once I did dedicated lines, I eliminated some highly regarded power conditioners- the system sounded better without them. (It's not that the dedicated lines 'improved' the sound, but they did eliminate one additional variable in AC power noise and interference and I generally have pretty quiet power, with the occaional spurious noise). Power conditioners and regenerators will make a difference, whether it is better is a separate question and depends in part on how nasty your AC is to begin with. (Note that I have invested in a very expensive power system for my next room, so I'm not negativing the value of dealing with AC power, just talking priorities, especially at a budget).
Racks- big improvement in that department, but you should know that even bigger improvements may be obtained by using a less fancy isolating rack and going with a very basic rack that allows you to use decoupling devices, like the Stillpoints. Having gone both ways (system currently uses some fancy Grand Prix Monaco stands and a very basic Adona platform combined with Stillpoints Ultra SS, you may find that the latter is more within budget and gives you considerable flexibility).
