from Southern California!

I will second the above advice. A simple sporran can be had quite inexpensively (try here: www.whatpriceglory.com). You may also try tartanista on Ebay (reasonable prices and okay quality. Also, usakilts.com have some decent sporrans for reasonable prices.

None of the above are top-notch quality sporrans but they will suffice reapectably until you can afford a nicer one.

Hose is certainly a must (although white is currently unfashionable in the kilt-owners-world-at-large). You can find some for around $16-$30 on Ebay, USAKilts.com, and Scotweb.co.uk. I would go with Lovat blue, Lovat green, claret, or charcoal (not black). Those colours will match any kilt for any occasion.

A white dress shirt is perfectly acceptable for pretty much any occasion (including a wedding). A tartan tie is perfectly fine (so-long as it matches your kilt). Other options are striped, solid, and patterned ties. Black (day or evening) or brown (day) shoes will suit you very well; I never wear ghillie brogues and don't own any.

A waistcoat (vest) would dress it up a bit more but is not required by any means.

I would, in all honesty, skip the belt. Unless you are attending a black tie event where 'bling' is 'king' it will be one more expense and headache to worry about.

Have a good time and best wishes!