Can't you find something else on the auction site that your higher authority would like? She can come along! Do you think she would notice that $525 extra purchase?
BTW, make sure whatever you get is a model you can lift and carry to your vehicle, and to the place you plan to put it. The big ones are heavy.
You probably wouldn't have worn out the Pro-Filer so quickly this time if you'd let a pro shop redo the ROH. I did the same thing once, and had to buy another stone. Pro-Filers are fine for touch-ups, but not for serious modifications.
(Unless Pro-Filers have changed, you only need to buy the new round stone, from Pro-Filer or elsewhere, not the whole kit. On mine, you can remove the pin that keeps the stone in with a pin punch, or equivalent.)
However, it sounds like you have decided you want a powered sharpening tool, so I bet you get one, one way or another. Tell us about your experiences!
While it might seem like the powered sharpener is a good deal economically, it is possible it will take off enough extra metal, compared to the hand tool, to more than make up for the cost of new Pro-Filer stones. I haven't found a skate tech who can take off less than about 0.003" on a competent sharpening with a powered sharpener. And the first few times, if your first tries are like my abortive tries, you will take off a good deal more metal at first.
Which incidentally means you shouldn't start with your good blades. Use old ones, or used ones. Rinks sometimes throw out old rentals, and may give them away if you ask.
Make your first attempts at centering the wheel on both sides of the blade, with the machine turned off (so you just scratch the metal), or by the time you are done, there won't be anything left of your blade. Also, before even doing the scratch, make sure you are close to centered, on both sides by using a precision calipers. And de-warp the blade if needed. (Some fancy blade holders clamp it straight.)
It's very important you get a incrementally adjustable blade holder - if you get one that holds the blade by pressure, so you loosen a bolt, move the blade, re-tighten, and try again, you will waste even more metal.