Using sucralose is a good idea - it is actually a kind of sugar, but is so concentrated that you need only a tiny amount, so it won't clog up your atty, like some other sugars will. Dont use Splenda- this contains maltodextrin, which is a naturally occuring sugar. Likewise, many other sweeteners, even liquid ones contain fillers and flavour regulators that will also make them impure and may damage your kit/health. Another great sweetener is Ethyl Maltol (EM) which is an ingredient in cotton candy/candy floss. This also adds a little bitterness to a mix and is a great "body" building agent. Hope this helps.
Sucralose can be bought from Liberty Flights but is very diluted. I get my sucralose as a pure powder and mix with PG in warm water. Ethyl Maltol is a trade ingredient and can usually only be bought in bulk, though some suppliers do it in smaller amounts. In UK, I buy from Ecigwizard.
Dan