Yay - a weekend project! I found eBay and Amazon a pain to search for non-polarized 220uf (and really hard to find 270uf), ended up at Frys 3 miles from my work. $2.89 each but no shipping cost and no waiting...
FRYS.com*|*NTE link for those interested. They're rather large...nearly the size of an AA battery, but I thought the 63V upgrade would be wise over the 16V alternative, based on other discussion in this thread.