If it were me, I would actually stick with a nice leather girth (no sheepskin/fleece). Probably leather or similar plain open-front boots, too. I feel like too much white and "flashiness" of tack detracts from the overall appearance. You're trying to show off yourself and your horse in equitation and hunters- you don't want the judge's eye fixated on your white girth :).
As for bridles, I own a Nunn Finer Hampton bridle, and so far it has held up well and looks great. However, it is lighter in color and I'm not sure it would match your saddle. Mine has darkened slightly when I oil it, but not tremendously. Nunn Finer does, I believe, have some darker-colored bridles, and the quality of mine is great.
Since you don't want to spend over $90 on a bridle, have you thought about buying one used? You can often find great deals on used bridles that are still in good condition.
For show pads, I personally just like a plain white fitted pad; keep it simple :). I feel like you can't go wrong with neat and clean traditional turnout and there are still small ways you can stand out that don't detract from the big picture.
haha sorry that was so long :)