Is $525 a "don't be a dummy, buy the gun" price, or is it "just fair" based on what I've described?
That price will put you into a nice used Winchester 94 or a Marlin 336. I am not saying the Henry is a poor choice or the price is not right but personally if I were in the market for a 30-30 (and I am not - I own three Winchesters) I would stick with certain 'traditions' when it comes to the 30-30, for a variety of reasons.
Maybe more importantly, what in the world would I do with a 30-30
Well that depends on you - IF you are planning on hunting MOST deer are shot at ranges that a .357 would be entirely adequate for. Depending on where you live you may be dramatically limited on range due to the environment and a .357 might be just fine.
While the 30- 30 may have a marked advantage in range over the .357 It's not so dramatic as to be of a GREAT advantage over a .357. My point being if you feel shots might be taken at say 150 - 200 yards or more then a rifle with a more powerful caliber should be chosen to start with. You don't want to be in a hunting environment where a 200 + yard shot (or more) might be a possibility and only have a .357 - or a 30-30.
Where I live long distance shots 300-400+ yards are a possibility and I typically hunt with a .243 Winchester but because I did not draw any tags this year I may buy a general Western Oregon deer tag and travel a short distance just inside the Western Oregon region where the woods are much thicker and shots can be as close as a few yards to really probably no more than 75 maybe and my .357 BBB or one of my 30-30s will be just fine. Heck I may hunt with my 1899 Winchester Klondike Sporting Rifle - at 118 years old it is still a tackdriver!
To summarize I love the 30-30, reload and shoot mine often with most of it being offhand field shooting at varmints or random targets. The Henry is a great rifle and I love my .357 BBB but for a 30-30 I Believe one is better served with a Winchester or Marlin and I often see both in good, used condition in the $500 (or less) price range.