Welcome aboard, Cryglory.
Are you REALLY sure you want the Happ "Ultimate" stick??
The reviews that I've read agree that Happ's "Ultimate" is "Ultimate" in name only.

The fact that the three largest resellers/suppliers here don't carry it should be a bit of a warning.
If you want Happ sticks, you might want to consider the Happ Supers or Competitions instead.
Depending on your gaming genre preferences, another stick may be better.
What kind of games do you prefer?
Old-school classics, shmups, and fighting games all have different sticks that work well for that genre.
In addition to
Ultimarc, check out
Groovy Game Gear and
Paradise Arcade Shop.
Andy, Randy, and Bryan -- the respective business owners -- are regulars around here.
If you want something from Happ (or Ultimarc) that Randy or Bryan don't have on their sites, check on
ArcadeEmulator.net to see if Divemaster127 has it -- 90%+ chance Gary's got it. (even if the site doesn't list it)
Also he doesn't charge nearly as much for shipping as Happ does.
As far as the 4-way/8-way goes, both use 4 switch inputs -- the 8-way can close up to two switches at a time.
+1 on only using 6 buttons per player unless you are
certain you'll be adding console games that need that many.
If you decide to add the later consoles, (>6 buttons) you may also consider using a USB port to plug in the original gamepads instead since the "shoulder" buttons are often directional and the games are designed for that controller.
+1 on using a spreadsheet to add up costs -- include hyperlinks for easy ordering.

Also, be sure to get something nice for the wife and try to find some games she likes.
Once she's hooked on Bubble Bobble or Puzzle Bobble, it'll be easier to pitch the next build/upgrade.

Scott