I found some nice and cheap cyrillic keyboard stickers on amazon
Those seem to be Russian only, however, on eBay you can find Ukrainian stickers even cheaper
Edit: seems my link is being corrupted, just search on eBay for 'Ukrainian keyboard stickers' they should be around $1.50-$2.00
If you don't use phonetic layout you'll have a very difficult time without those stickers, trust me. Even with phonetic layout that I use on my pc I purchased stickers because there 6-7 letters that you can't map on standard English keyboard (26vs33 letters) and I would always forget a few. Stickers make it little easier in that regard.