Flying through with a Whining Wrist

I've decided to jump, head-first, into this one. It's such a beautiful pattern, I couldn't resist!

As is my usual MO, I plan on modding this sweetie. First off, I decided to use a stash-yarn, which unfortunate is going to prove a gamble: I have 10 skeins of Jamieson's DK in Port Wine (a lovely colour!) which only amounts to 1075 metres of yarny goodness.
With this in mind, I've decided to shorten the sleeves, probably to just above the elbow.

Also, as I was working along, I noticed my row count is abnormally high! I hope this means I won't use up as much yarn.

I've also nipped in the waist a bit, (once again, in a desperate attempt to save some for what I imagine will be a yarn-gobbling yoke and tedious ribbed edging).

Now, off to knit. I do have one nagging problem - what colour buttons to buy? Any suggestions? I think it may be tricky to match the purple. Would a pearly white be too stark a contrast? How about slate grey?
Thanks!

Yarn purchased

I purchased my yarn today! I am going with Knit Picks Swish DK in Moss. Since its my first sweater I wanted to go with something that wouldn't break the bank. I can't wait to get my hands on it - such a beautiful shade of green. I debated going with a pink shade, but in the end green won! I have another couple of projects on the needles now but will probably get to it in a few weeks.