Badbong, those prices seem about right for what you're getting. Have you tried the "official" resellers listed on the Kumho website? Prices are
roughly proportional to wheel diameter. I was recently quoted $229 in 245/35R18 and $219 in 215/40R18 for KU31, so that's $896 per set, fitted and balanced. KU36 were $279/$250 respectively (except 225/40R18), $1058 per set. That was from Kay's Tyres in Albion Park Rail. One or the other will be going on my 135i as soon as I finish off the runcraps. OEM RE050As runcraps were over $700 per tyre!
Keep in mind that KU31s have a pretty high treadwear rating (around 300 I think), so they're probably not quite as sticky as other performance tyres (tread depth is pretty normal, so the rating is mostly about wear rate / tyre hardness).
Don't bother paying for an "alignment" from a tyre place. All they'll do is check it, not adjust anything. You're better off getting a proper four wheel alignment by a specialist.