In this video I demonstrate one of my miniature Russian single-lever morse paddles, which I purchased on eBay last year for around 20 euro apiece. These are light and dainty little keys, but very effective and easy to use. They would be quite transportable for SOTA or other portable or mobile activities.
Here is a link to the seller's page on eBay: http://www.ebay.co.uk/usr/wwwww337
He often has them for sale and seems to have a stock of them. Well worth the small spend in my opinion!